WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03AR3
Distribution Date: 09/27/2004

Class	Cusip	Orig Prin Bal	Begin Prin Bal	Int Rate Accrued	Int Rate Paid	Int Dist	Prin Dist	Int Shortfall	PPIS	Uncomp Int Shortfall	Prin Loss	Deferred Interest	Int Reimbursed	Unsched Int	Prin Reimbursed	Subsequent Recoveries	Total Dist	Ending Class Bal
IA	939336G23	$114,923,400.00	$47,221,648.82	3.5519854112%	3.5519854112%	$139,775.51	$6,511,760.55	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$6,651,536.06	$40,709,888.27
IIA1	939336G31	$23,850,000.00	$12,317,750.50	5.0621732489%	5.0621732489%	$51,962.16	$630,145.25	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$682,107.41	$11,687,605.25
IIA2	939336G49	$281,242,600.00	$145,252,670.18	4.0101732489%	4.0101732489%	$485,406.98	$7,430,762.64	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$7,916,169.61	$137,821,907.54
IIIA	939336G56	$54,528,100.00	$29,051,604.94	4.7859322415%	4.7859322415%	$115,865.84	$2,081,654.29	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$2,197,520.14	$26,969,950.65
IVA	939336G64	$110,100,000.00	$68,862,391.12	5.0403077075%	5.0403077075%	$289,239.70	$3,291,300.34	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$3,580,540.04	$65,571,090.78
VA	939336G72	$26,677,400.00	$15,789,734.37	5.1644714330%	5.1644714330%	$67,954.69	$317,216.41	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$385,171.10	$15,472,517.96
IX	939336G80	$114,923,400.00	$47,221,648.82	1.2280000000%	1.2280000000%	$48,323.49	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$48,323.49	$40,709,888.27
IIX	939336G98	$281,242,600.00	$145,252,670.18	1.0520000000%	1.0520000000%	$127,338.17	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$127,338.17	$137,821,907.54
M	939336H22	$27,509,500.00	$27,346,596.54	4.9851486526%	4.9851486526%	$113,605.71	$5,959.08	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$119,564.79	$27,340,637.46
B1	939336H30	$12,565,900.00	$12,491,488.29	4.9851486526%	4.9851486526%	$51,893.27	$2,722.01	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$54,615.29	$12,488,766.28
B2	939336H48	$9,509,600.00	$9,453,286.85	4.9851486526%	4.9851486526%	$39,271.70	$2,059.96	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$41,331.66	$9,451,226.89
B3	939336H55	$6,792,400.00	$6,752,177.32	4.9851486526%	4.9851486526%	$28,050.51	$1,471.36	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$29,521.87	$6,750,705.96
B4	939336H71	$7,132,100.00	$7,089,865.72	4.9851486526%	4.9851486526%	$29,453.36	$1,544.95	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$30,998.31	$7,088,320.77
B5	939336H89	$2,377,400.00	$2,363,321.71	4.9851486526%	4.9851486526%	$9,817.93	$514.99	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$10,332.92	$2,362,806.72
B6	939336H97	$2,037,990.89	$2,025,922.46	4.9851486526%	4.9851486526%	$8,416.27	$441.47	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$8,857.74	$2,025,480.99
R	939336H63	$100.00	$0.00	0.0000000000%	0.0000000000%	$0.09	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.09	$0.00
R_SYN	XXXXXXXXX	$0.00	$0.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
Total		$679,246,490.89	$386,018,458.82			$1,606,375.37	$20,277,553.31	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$21,883,928.68	$365,740,905.51

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03AR3
Distribution Date: 09/27/2004

Class	Orig Face	Beg Bal	Prin Loss	Prin Reimbursed	Subsequent Recoveries	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
IA	$114,923,400.00	$47,221,648.82	$0.00	$0.00	$0.00	$0.00	$6,511,760.55	0.3542349797	$40,709,888.27
IIA1	$23,850,000.00	$12,317,750.50	$0.00	$0.00	$0.00	$0.00	$630,145.25	0.4900463417	$11,687,605.25
IIA2	$281,242,600.00	$145,252,670.18	$0.00	$0.00	$0.00	$0.00	$7,430,762.64	0.4900463427	$137,821,907.54
IIIA	$54,528,100.00	$29,051,604.94	$0.00	$0.00	$0.00	$0.00	$2,081,654.29	0.4946064625	$26,969,950.65
IVA	$110,100,000.00	$68,862,391.12	$0.00	$0.00	$0.00	$0.00	$3,291,300.34	0.5955594076	$65,571,090.78
VA	$26,677,400.00	$15,789,734.37	$0.00	$0.00	$0.00	$0.00	$317,216.41	0.5799859791	$15,472,517.96
IX	$114,923,400.00	$47,221,648.82	$0.00	$0.00	$0.00	$0.00	$0.00	0.3542349797	$40,709,888.27
IIX	$281,242,600.00	$145,252,670.18	$0.00	$0.00	$0.00	$0.00	$0.00	0.4900463427	$137,821,907.54
M	$27,509,500.00	$27,346,596.54	$0.00	$0.00	$0.00	$0.00	$5,959.08	0.9938616645	$27,340,637.46
B1	$12,565,900.00	$12,491,488.29	$0.00	$0.00	$0.00	$0.00	$2,722.01	0.9938616637	$12,488,766.28
B2	$9,509,600.00	$9,453,286.85	$0.00	$0.00	$0.00	$0.00	$2,059.96	0.9938616651	$9,451,226.89
B3	$6,792,400.00	$6,752,177.32	$0.00	$0.00	$0.00	$0.00	$1,471.36	0.9938616630	$6,750,705.96
B4	$7,132,100.00	$7,089,865.72	$0.00	$0.00	$0.00	$0.00	$1,544.95	0.9938616635	$7,088,320.77
B5	$2,377,400.00	$2,363,321.71	$0.00	$0.00	$0.00	$0.00	$514.99	0.9938616640	$2,362,806.72
B6	$2,037,990.89	$2,025,922.46	$0.00	$0.00	$0.00	$0.00	$441.47	0.9938616507	$2,025,480.99
R	$100.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
R_SYN	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
Total	$679,246,490.89	$386,018,458.82	$0.00	$0.00	$0.00	$0.00	$20,277,553.31	0.5384509312	$365,740,905.51

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03AR3
Distribution Date: 09/27/2004
PER $1000 DENOMINATION
Class	Orig Face	Beg Bal	Prin Loss	Prin Reimbursed	Subsequent Recoveries	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
IA	$114,923,400.00	410.89672617	0.00000000	0.00000000	0.00000000	0.00000000	56.66174643	0.3542349797	354.23497973
IIA1	$23,850,000.00	516.46752621	0.00000000	0.00000000	0.00000000	0.00000000	26.42118449	0.4900463417	490.04634172
IIA2	$281,242,600.00	516.46752725	0.00000000	0.00000000	0.00000000	0.00000000	26.42118456	0.4900463427	490.04634269
IIIA	$54,528,100.00	532.78227079	0.00000000	0.00000000	0.00000000	0.00000000	38.17580825	0.4946064625	494.60646254
IVA	$110,100,000.00	625.45314369	0.00000000	0.00000000	0.00000000	0.00000000	29.89373606	0.5955594076	595.55940763
VA	$26,677,400.00	591.87680846	0.00000000	0.00000000	0.00000000	0.00000000	11.89082932	0.5799859791	579.98597914
IX	$114,923,400.00	410.89672617	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.3542349797	354.23497973
IIX	$281,242,600.00	516.46752725	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.4900463427	490.04634269
M	$27,509,500.00	994.07828350	0.00000000	0.00000000	0.00000000	0.00000000	0.21661899	0.9938616645	993.86166452
B1	$12,565,900.00	994.07828249	0.00000000	0.00000000	0.00000000	0.00000000	0.21661879	0.9938616637	993.86166371
B2	$9,509,600.00	994.07828405	0.00000000	0.00000000	0.00000000	0.00000000	0.21661900	0.9938616651	993.86166505
B3	$6,792,400.00	994.07828161	0.00000000	0.00000000	0.00000000	0.00000000	0.21661857	0.9938616630	993.86166304
B4	$7,132,100.00	994.07828269	0.00000000	0.00000000	0.00000000	0.00000000	0.21661923	0.9938616635	993.86166347
B5	$2,377,400.00	994.07828300	0.00000000	0.00000000	0.00000000	0.00000000	0.21661900	0.9938616640	993.86166400
B6	$2,037,990.89	994.07827088	0.00000000	0.00000000	0.00000000	0.00000000	0.21662020	0.9938616507	993.86165068
R	$100.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
R_SYN	$0.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03AR3
Distribution Date: 09/27/2004

Class	Orig Face	Int Rate Accrued	Int Rate Paid	Beg Cert Prin/Not Bal	Current Int Accrued	Int Shortfall	PPIS	Uncompensated Int Shortfall	Unscheduled Int	Int Reimbursed	Total Int Dist
IA	$114,923,400.00	3.5519854112%	3.5519854112%	$47,221,648.82	$139,775.51	$0.00	$0.00	$0.00	$0.00	$0.00	$139,775.51
IIA1	$23,850,000.00	5.0621732489%	5.0621732489%	$12,317,750.50	$51,962.16	$0.00	$0.00	$0.00	$0.00	$0.00	$51,962.16
IIA2	$281,242,600.00	4.0101732489%	4.0101732489%	$145,252,670.18	$485,406.98	$0.00	$0.00	$0.00	$0.00	$0.00	$485,406.98
IIIA	$54,528,100.00	4.7859322415%	4.7859322415%	$29,051,604.94	$115,865.84	$0.00	$0.00	$0.00	$0.00	$0.00	$115,865.84
IVA	$110,100,000.00	5.0403077075%	5.0403077075%	$68,862,391.12	$289,239.70	$0.00	$0.00	$0.00	$0.00	$0.00	$289,239.70
VA	$26,677,400.00	5.1644714330%	5.1644714330%	$15,789,734.37	$67,954.69	$0.00	$0.00	$0.00	$0.00	$0.00	$67,954.69
IX	$114,923,400.00	1.2280000000%	1.2280000000%	$47,221,648.82	$48,323.49	$0.00	$0.00	$0.00	$0.00	$0.00	$48,323.49
IIX	$281,242,600.00	1.0520000000%	1.0520000000%	$145,252,670.18	$127,338.17	$0.00	$0.00	$0.00	$0.00	$0.00	$127,338.17
M	$27,509,500.00	4.9851486526%	4.9851486526%	$27,346,596.54	$113,605.71	$0.00	$0.00	$0.00	$0.00	$0.00	$113,605.71
B1	$12,565,900.00	4.9851486526%	4.9851486526%	$12,491,488.29	$51,893.27	$0.00	$0.00	$0.00	$0.00	$0.00	$51,893.27
B2	$9,509,600.00	4.9851486526%	4.9851486526%	$9,453,286.85	$39,271.70	$0.00	$0.00	$0.00	$0.00	$0.00	$39,271.70
B3	$6,792,400.00	4.9851486526%	4.9851486526%	$6,752,177.32	$28,050.51	$0.00	$0.00	$0.00	$0.00	$0.00	$28,050.51
B4	$7,132,100.00	4.9851486526%	4.9851486526%	$7,089,865.72	$29,453.36	$0.00	$0.00	$0.00	$0.00	$0.00	$29,453.36
B5	$2,377,400.00	4.9851486526%	4.9851486526%	$2,363,321.71	$9,817.93	$0.00	$0.00	$0.00	$0.00	$0.00	$9,817.93
B6	$2,037,990.89	4.9851486526%	4.9851486526%	$2,025,922.46	$8,416.27	$0.00	$0.00	$0.00	$0.00	$0.00	$8,416.27
R	$100.00	0.0000000000%	0.0000000000%	$0.00	$0.09	$0.00	$0.00	$0.00	$0.00	$0.00	$0.09
R_SYN	$0.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
Total	$679,246,490.89			$386,018,458.82	$1,606,375.37	$0.00	$0.00	$0.00	$0.00	$0.00	$1,606,375.37

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03AR3
Distribution Date: 09/27/2004
PER $1000 DENOMINATION
Class	Orig Face	Int Rate Accrued	Int Rate Paid	Beg Cert Prin/Not Bal	Curent Int Accrued	Int Shortfall	PPIS	Uncompensated Int Shortfall	Unscheduled Int	Int Reimbursed	Total Int Dist
IA	$114,923,400.00	3.5519854112%	3.5519854112%	410.89672617	1.21624935	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	1.21624935
IIA1	$23,850,000.00	5.0621732489%	5.0621732489%	516.46752621	2.17870692	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.17870692
IIA2	$281,242,600.00	4.0101732489%	4.0101732489%	516.46752725	1.72593690	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	1.72593690
IIIA	$54,528,100.00	4.7859322415%	4.7859322415%	532.78227079	2.12488313	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.12488313
IVA	$110,100,000.00	5.0403077075%	5.0403077075%	625.45314369	2.62706358	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.62706358
VA	$26,677,400.00	5.1644714330%	5.1644714330%	591.87680846	2.54727560	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.54727560
IX	$114,923,400.00	1.2280000000%	1.2280000000%	410.89672617	0.42048434	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.42048434
IIX	$281,242,600.00	1.0520000000%	1.0520000000%	516.46752725	0.45276985	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.45276985
M	$27,509,500.00	4.9851486526%	4.9851486526%	994.07828350	4.12969011	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	4.12969011
B1	$12,565,900.00	4.9851486526%	4.9851486526%	994.07828249	4.12968987	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	4.12968987
B2	$9,509,600.00	4.9851486526%	4.9851486526%	994.07828405	4.12969000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	4.12969000
B3	$6,792,400.00	4.9851486526%	4.9851486526%	994.07828161	4.12969054	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	4.12969054
B4	$7,132,100.00	4.9851486526%	4.9851486526%	994.07828269	4.12968971	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	4.12968971
B5	$2,377,400.00	4.9851486526%	4.9851486526%	994.07828300	4.12969210	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	4.12969210
B6	$2,037,990.89	4.9851486526%	4.9851486526%	994.07827088	4.12968971	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	4.12968971
R	$100.00	0.0000000000%	0.0000000000%	0.00000000	0.90000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.90000000
R_SYN	$0.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03AR3
WEIGHTED AVERAGE PC RATE: 4.77999%
WEIGHTED AVERAGE MATURITY: 340.99975
WEIGHTED AVERAGE LOAN AGE: 16.54405
POOL NUMBER: 2127
ISSUE DATE: 06/26/2003
CERTIFICATE BALANCE AT ISSUE: $127,692,778.44
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	120		$59,873,939.21
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$11,466.60
Unscheduled Principal Collection/Reversals		$7,572.85
Liquidations-in-full	11	$6,495,144.17
Subsequent Recoveries		$0.00
Net principal Distributed		$6,514,183.62	-$6,514,183.62

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	109		$53,359,755.59

SCHEDULED INTEREST AT MORTGAGE RATE:		$258,455.13

UNSCHEDULED INTEREST AT MORTGAGE RATE:
Unscheduled Interest Collection/Reversals		$0.00
Interest Uncollected on Liquidation		$0.00
Interest Uncollected on Non-Earning Assets		$0.00
Interest Uncollected on Prepayment		$0.00
Uncompensated Uncollected Interest		$0.00
Net Unscheduled Interest Distributed		$0.00

OTHER:
Loan Conversion Fees		$0.00
Expense Reimbursements		$0.00
Gain on Liquidations		$0.00
Hazard Insurance Premium Refunds		$0.00
Recoveries Carried Forward		$0.00
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$19,957.97

UNSCHEDULED SERVICING FEES:
Unscheduled Service Fee Collections/Reversals		$0.00
Servicing Fees Uncollected on Liquidation		$0.00
Servicing Fees Uncollected/Non-Earning Assets		$0.00
Net Unscheduled Service Fees Distributed		$0.00

MISCELLANEOUS EXPENSES:		$0.00

NET FUNDS DISTRIBUTED:		$6,752,680.78

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03AR3
WEIGHTED AVERAGE PC RATE: 5.06217%
WEIGHTED AVERAGE MATURITY: 343.35916
WEIGHTED AVERAGE LOAN AGE: 16.55764
POOL NUMBER: 2128
ISSUE DATE: 06/26/2003
CERTIFICATE BALANCE AT ISSUE: $338,991,832.94
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	384		$191,386,699.31
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$33,314.30
Unscheduled Principal Collection/Reversals		$13,467.27
Liquidations-in-full	17	$8,020,012.65
Subsequent Recoveries		$0.00
Net principal Distributed		$8,066,794.22	-$8,066,794.22

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	367		$183,319,905.09

SCHEDULED INTEREST AT MORTGAGE RATE:		$871,156.10

UNSCHEDULED INTEREST AT MORTGAGE RATE:
Unscheduled Interest Collection/Reversals		$0.00
Interest Uncollected on Liquidation		$0.00
Interest Uncollected on Non-Earning Assets		$0.00
Interest Uncollected on Prepayment		$0.00
Uncompensated Uncollected Interest		$0.00
Net Unscheduled Interest Distributed		$0.00

OTHER:
Loan Conversion Fees		$0.00
Expense Reimbursements		$0.00
Gain on Liquidations		$0.00
Hazard Insurance Premium Refunds		$0.00
Recoveries Carried Forward		$0.00
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$63,795.51

UNSCHEDULED SERVICING FEES:
Unscheduled Service Fee Collections/Reversals		$0.00
Servicing Fees Uncollected on Liquidation		$0.00
Servicing Fees Uncollected/Non-Earning Assets		$0.00
Net Unscheduled Service Fees Distributed		$0.00

MISCELLANEOUS EXPENSES:		$0.00

NET FUNDS DISTRIBUTED:		$8,874,154.81

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03AR3
WEIGHTED AVERAGE PC RATE: 4.78593%
WEIGHTED AVERAGE MATURITY: 342.42662
WEIGHTED AVERAGE LOAN AGE: 16.54046
POOL NUMBER: 2129
ISSUE DATE: 06/26/2003
CERTIFICATE BALANCE AT ISSUE: $60,586,857.57
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	177		$35,061,041.29
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$10,421.14
Unscheduled Principal Collection/Reversals		$3,475.01
Liquidations-in-full	10	$2,069,544.32
Subsequent Recoveries		$0.00
Net principal Distributed		$2,083,440.47	-$2,083,440.47

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	167		$32,977,600.82

SCHEDULED INTEREST AT MORTGAGE RATE:		$151,520.11

UNSCHEDULED INTEREST AT MORTGAGE RATE:
Unscheduled Interest Collection/Reversals		$0.00
Interest Uncollected on Liquidation		$0.00
Interest Uncollected on Non-Earning Assets		$0.00
Interest Uncollected on Prepayment		$0.00
Uncompensated Uncollected Interest		$0.00
Net Unscheduled Interest Distributed		$0.00

OTHER:
Loan Conversion Fees		$0.00
Expense Reimbursements		$0.00
Gain on Liquidations		$0.00
Hazard Insurance Premium Refunds		$0.00
Recoveries Carried Forward		$0.00
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$11,686.94

UNSCHEDULED SERVICING FEES:
Unscheduled Service Fee Collections/Reversals		$0.00
Servicing Fees Uncollected on Liquidation		$0.00
Servicing Fees Uncollected/Non-Earning Assets		$0.00
Net Unscheduled Service Fees Distributed		$0.00

MISCELLANEOUS EXPENSES:		$0.00

NET FUNDS DISTRIBUTED:		$2,223,273.64

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03AR3
WEIGHTED AVERAGE PC RATE: 5.04031%
WEIGHTED AVERAGE MATURITY: 342.96566
WEIGHTED AVERAGE LOAN AGE: 16.58762
POOL NUMBER: 2130
ISSUE DATE: 06/26/2003
CERTIFICATE BALANCE AT ISSUE: $122,333,366.95
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	389		$81,020,298.39
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$22,587.89
Unscheduled Principal Collection/Reversals		$12,487.29
Liquidations-in-full	14	$3,259,614.70
Subsequent Recoveries		$0.00
Net principal Distributed		$3,294,689.88	-$3,294,689.88

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	375		$77,725,608.51

SCHEDULED INTEREST AT MORTGAGE RATE:		$367,312.82

UNSCHEDULED INTEREST AT MORTGAGE RATE:
Unscheduled Interest Collection/Reversals		$0.00
Interest Uncollected on Liquidation		$0.00
Interest Uncollected on Non-Earning Assets		$0.00
Interest Uncollected on Prepayment		$0.00
Uncompensated Uncollected Interest		$0.00
Net Unscheduled Interest Distributed		$0.00

OTHER:
Loan Conversion Fees		$0.00
Expense Reimbursements		$0.00
Gain on Liquidations		$0.00
Hazard Insurance Premium Refunds		$0.00
Recoveries Carried Forward		$0.00
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$27,006.87

UNSCHEDULED SERVICING FEES:
Unscheduled Service Fee Collections/Reversals		$0.00
Servicing Fees Uncollected on Liquidation		$0.00
Servicing Fees Uncollected/Non-Earning Assets		$0.00
Net Unscheduled Service Fees Distributed		$0.00

MISCELLANEOUS EXPENSES:		$0.00

NET FUNDS DISTRIBUTED:		$3,634,995.83

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03AR3
WEIGHTED AVERAGE PC RATE: 5.16447%
WEIGHTED AVERAGE MATURITY: 342.13174
WEIGHTED AVERAGE LOAN AGE: 17.46174
POOL NUMBER: 2131
ISSUE DATE: 06/26/2003
CERTIFICATE BALANCE AT ISSUE: $29,641,654.99
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	49		$18,676,480.63
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$7,949.44
Unscheduled Principal Collection/Reversals		$5,723.09
Liquidations-in-full	1	$304,772.59
Subsequent Recoveries		$0.00
Net principal Distributed		$318,445.12	-$318,445.12

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	48		$18,358,035.51

SCHEDULED INTEREST AT MORTGAGE RATE:		$86,603.97

UNSCHEDULED INTEREST AT MORTGAGE RATE:
Unscheduled Interest Collection/Reversals		$0.00
Interest Uncollected on Liquidation		$0.00
Interest Uncollected on Non-Earning Assets		$0.00
Interest Uncollected on Prepayment		$0.00
Uncompensated Uncollected Interest		$0.00
Net Unscheduled Interest Distributed		$0.00

OTHER:
Loan Conversion Fees		$0.00
Expense Reimbursements		$0.00
Gain on Liquidations		$0.00
Hazard Insurance Premium Refunds		$0.00
Recoveries Carried Forward		$0.00
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$6,225.47

UNSCHEDULED SERVICING FEES:
Unscheduled Service Fee Collections/Reversals		$0.00
Servicing Fees Uncollected on Liquidation		$0.00
Servicing Fees Uncollected/Non-Earning Assets		$0.00
Net Unscheduled Service Fees Distributed		$0.00

MISCELLANEOUS EXPENSES:		$0.00

NET FUNDS DISTRIBUTED:		$398,823.62

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03AR3
WEIGHTED AVERAGE PC RATE: 4.99367%
WEIGHTED AVERAGE MATURITY: 342.78562
WEIGHTED AVERAGE LOAN AGE: 16.60586
POOL NUMBER: Group 1
ISSUE DATE: 06/26/2003
CERTIFICATE BALANCE AT ISSUE: $679,246,490.89
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	1119		$386,018,458.83
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$85,739.37
Unscheduled Principal Collection/Reversals		$42,725.51
Liquidations-in-full	53	$20,149,088.43
Subsequent Recoveries		$0.00
Net principal Distributed		$20,277,553.31	-$20,277,553.31

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	1066		$365,740,905.52

SCHEDULED INTEREST AT MORTGAGE RATE:		$1,735,048.13

UNSCHEDULED INTEREST AT MORTGAGE RATE:
Unscheduled Interest Collection/Reversals		$0.00
Interest Uncollected on Liquidation		$0.00
Interest Uncollected on Non-Earning Assets		$0.00
Interest Uncollected on Prepayment		$0.00
Uncompensated Uncollected Interest		$0.00
Net Unscheduled Interest Distributed		$0.00

OTHER:
Loan Conversion Fees		$0.00
Expense Reimbursements		$0.00
Gain on Liquidations		$0.00
Hazard Insurance Premium Refunds		$0.00
Recoveries Carried Forward		$0.00
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$128,672.76

UNSCHEDULED SERVICING FEES:
Unscheduled Service Fee Collections/Reversals		$0.00
Servicing Fees Uncollected on Liquidation		$0.00
Servicing Fees Uncollected/Non-Earning Assets		$0.00
Net Unscheduled Service Fees Distributed		$0.00

MISCELLANEOUS EXPENSES:		$0.00

NET FUNDS DISTRIBUTED:		$21,883,928.68

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03AR3
WEIGHTED AVERAGE PC RATE: 4.99367%
WEIGHTED AVERAGE MATURITY: 342.78562
WEIGHTED AVERAGE LOAN AGE: 16.60586
POOL NUMBER: ALL
ISSUE DATE: 06/26/2003
CERTIFICATE BALANCE AT ISSUE: $679,246,490.89
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	1119		$386,018,458.83
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$85,739.37
Unscheduled Principal Collection/Reversals		$42,725.51
Liquidations-in-full	53	$20,149,088.43
Subsequent Recoveries		$0.00
Net principal Distributed		$20,277,553.31	-$20,277,553.31

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	1066		$365,740,905.52

SCHEDULED INTEREST AT MORTGAGE RATE:		$1,735,048.13

UNSCHEDULED INTEREST AT MORTGAGE RATE:
Unscheduled Interest Collection/Reversals		$0.00
Interest Uncollected on Liquidation		$0.00
Interest Uncollected on Non-Earning Assets		$0.00
Interest Uncollected on Prepayment		$0.00
Uncompensated Uncollected Interest		$0.00
Net Unscheduled Interest Distributed		$0.00

OTHER:
Loan Conversion Fees		$0.00
Expense Reimbursements		$0.00
Gain on Liquidations		$0.00
Hazard Insurance Premium Refunds		$0.00
Recoveries Carried Forward		$0.00
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
09/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$128,672.76

UNSCHEDULED SERVICING FEES:
Unscheduled Service Fee Collections/Reversals		$0.00
Servicing Fees Uncollected on Liquidation		$0.00
Servicing Fees Uncollected/Non-Earning Assets		$0.00
Net Unscheduled Service Fees Distributed		$0.00

MISCELLANEOUS EXPENSES:		$0.00

NET FUNDS DISTRIBUTED:		$21,883,928.68

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03AR3
Distribution Date: 09/27/2004

Distribution by Group
Pool ID		Principal		Interest		Total
Pool - 2127		$6,514,183.62		$238,497.16		$6,752,680.78
Pool - 2128		$8,066,794.22		$807,360.59		$8,874,154.81
Pool - 2129		$2,083,440.47		$139,833.17		$2,223,273.64
Pool - 2130		$3,294,689.88		$340,305.95		$3,634,995.83
Pool - 2131		$318,445.12		$80,378.50		$398,823.62
Group 1		$20,277,553.31		$1,606,375.37		$21,883,928.68
Aggregate		$20,277,553.31		$1,606,375.37		$21,883,928.68

Number of Loans and Aggregate Principal Balance By Group
Pool ID	Beg Bal	Beg Count	Paid Off / Liq Count	Rem Count	Sched Prin End Bal	Sched Prin	Prin PrePay / Liq	Unsched Prin / Rev	Total Prin
Pool - 2127	$59,873,939.21	120	11	109	$53,359,755.59	$11,466.60	$6,495,144.17	$7,572.85	$6,514,183.62
Pool - 2128	$191,386,699.31	384	17	367	$183,319,905.09	$33,314.30	$8,020,012.65	$13,467.27	$8,066,794.22
Pool - 2129	$35,061,041.29	177	10	167	$32,977,600.82	$10,421.14	$2,069,544.32	$3,475.01	$2,083,440.47
Pool - 2130	$81,020,298.39	389	14	375	$77,725,608.51	$22,587.89	$3,259,614.70	$12,487.29	$3,294,689.88
Pool - 2131	$18,676,480.63	49	1	48	$18,358,035.51	$7,949.44	$304,772.59	$5,723.09	$318,445.12
Group 1	$386,018,458.83	1119	53	1066	$365,740,905.52	$85,739.37	$20,149,088.43	$42,725.51	$20,277,553.31
Aggregate	$386,018,458.83	1119	53	1066	$365,740,905.52	$85,739.37	$20,149,088.43	$42,725.51	$20,277,553.31

Delinquency Information by Group
Pool ID	1 Month Count	Sched End Balance	2 Months Count	Sched End Balance	3 Months Count	Sched End Balance	4 Months Count	Sched End Balance
Pool - 2127	1	$379,813.33	0	$0.00	0	$0.00	0	$0.00
Pool - 2128	2	$781,379.96	0	$0.00	0	$0.00	0	$0.00
Pool - 2129	5	$862,888.14	0	$0.00	0	$0.00	0	$0.00
Pool - 2130	5	$903,075.52	2	$395,868.00	0	$0.00	0	$0.00
Pool - 2131	0	$0.00	0	$0.00	0	$0.00	0	$0.00
Group 1	13	$2,927,156.95	2	$395,868.00	0	$0.00	0	$0.00
Aggregate	13	$2,927,156.95	2	$395,868.00	0	$0.00	0	$0.00

Foreclosure and REO Information by Group
Pool ID		Foreclosure Count		Sched End Balance		REO Count		Sched End Balance
Pool - 2127		0		$0.00		0		$0.00
Pool - 2128		3		$1,591,414.37		0		$0.00
Pool - 2129		1		$270,859.33		0		$0.00
Pool - 2130		3		$609,970.86		0		$0.00
Pool - 2131		0		$0.00		0		$0.00
Group 1		7		$2,472,244.56		0		$0.00
Aggregate		7		$2,472,244.56		0		$0.00

Aggregate Loss Amounts by Group
Pool ID			Count			Loss Amount
Pool - 2127			0			$0.00
Pool - 2128			0			$0.00
Pool - 2129			0			$0.00
Pool - 2130			0			$0.00
Pool - 2131			0			$0.00
Group 1			0			$0.00
Aggregate			0			$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03AR3
Distribution Date: 09/27/2004

INSURANCE RESERVES - Group 1
Insurance Type	Original Balance	Claims In Progress	Claims Paid	Coverage Adjustments	Coverage Remaining
MPI	$0.00	$0.00	$0.00	$0.00	$0.00
Special Hazard	$6,792,464.00	$0.00	$0.00	$0.00	$6,792,464.00
Bankruptcy Bond
Single-Units	$150,000.00	$0.00	$0.00	$0.00	$150,000.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$20,377,394.00	$0.00	$0.00	$0.00	$20,377,394.00

INSURANCE RESERVES - Aggregate
Insurance Type	Original Balance	Claims In Progress	Claims Paid	Coverage Adjustments	Coverage Remaining
MPI	$0.00	$0.00	$0.00	$0.00	$0.00
Special Hazard	$6,792,464.00	$0.00	$0.00	$0.00	$6,792,464.00
Bankruptcy Bond
Single-Units	$150,000.00	$0.00	$0.00	$0.00	$150,000.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$20,377,394.00	$0.00	$0.00	$0.00	$20,377,394.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03AR3
Distribution Date: 09/27/2004

The Group B Certificates provide, to the limited extent described in the Prospectus Supplement, credit support, as well as special hazard, bankruptcy, and fraud coverage to certain Group I, II, III,IV, V and Class M Certificates. The "Prospectus Supplement" is that certain Prospectus Supplement, dated June 24, 2003 to that certain Prospectus Supplement, dated May 20, 2003, to which certain Group I, II, III, IV, V, and Class M Certificates were offered. The Special Hazard, Bankruptcy, and Fraud coverage (collectively, "Credit Enhancements") provided by the B certificates provide coverage to the Group I, II, III,IV, V, and Class M Loans, subject to the conditions and limitations to payment specified thereunder.



The Class Principal Balances of each Class of the Class M,B1,B2,B3,B4,B5,B6 Certificatesimmediately after the principal and interest distribution on 200409 are as follows:

Class			Class Principal Balance
M			$27,340,637.46
B1			$12,488,766.28
B2			$9,451,226.89
B3			$6,750,705.96
B4			$7,088,320.77
B5			$2,362,806.72
B6			$2,025,480.99
Total			$67,507,945.06
Capitalized items used but not defined herein have the meanings ascribed to them in the Prospectus Supplement.
The amount of the special hazard coverage, bankruptcy coverage, and fraud coverage, as of the above referenced distribution date, is $6,792,464.00, $150,000.00, $20,377,394.00 respectively, and such coverages are referred to in the table above under the column "Insurance Type" as "special hazard," "bankruptcy bond," and "mortgage repurchase," respectively. However, no policy of insurance exists for any such coverage, notwithstanding the reference to "insurance."

MSC MORTGAGE PASS THROUGH CERTIFICATES SERIES 2003-AR3 8-K