WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.03AR4
Distribution Date: 10/27/2003

Class	Cusip	Orig Prin Bal	Begin Prin Bal	Int Rate Accrued	Int Rate Paid	Int Dist	Prin Dist	Int Shortfall	Prin Loss	Deferred Interest	Int Reimbursed	Unscheduled Int	Prin Reimbursed	Subsequent Recoveries	Total Dist	Ending Class Bal
A1	929227L38	$249,500,000.00	$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
A2	929227L46	$115,300,000.00	$100,766,822.58	2.2070000000%	2.2070000000%	$185,326.98	$58,512,257.98	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$58,697,584.96	$42,254,564.60
A3	929227L53	$170,000,000.00	$170,000,000.00	2.8750000000%	2.8750000000%	$407,291.67	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$407,291.67	$170,000,000.00
A4	929227L61	$123,700,000.00	$123,700,000.00	3.3630000000%	3.3630000000%	$346,669.25	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$346,669.25	$123,700,000.00
A5	929227L79	$110,200,000.00	$110,200,000.00	3.5510000000%	3.5510000000%	$326,100.17	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$326,100.17	$110,200,000.00
A6	929227L87	$244,878,000.00	$244,878,000.00	3.4230000000%	3.4230000000%	$698,514.50	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$698,514.50	$244,878,000.00
A7	929227L95	$200,000,000.00	$147,900,767.88	3.9500000000%	3.9500000000%	$486,840.03	$11,545,684.29	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$12,032,524.32	$136,355,083.59
X1	929227M29	$1,013,578,000.00	$749,544,822.58	1.1810000000%	1.1810000000%	$737,677.03	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$737,677.03	$691,032,564.60
X2	929227M37	$200,000,000.00	$147,900,767.88	0.7675495788%	0.7675495788%	$94,600.98	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$94,600.98	$136,355,083.59
B1	929227M45	$13,109,000.00	$13,085,718.53	4.7175495788%	4.7175495788%	$51,443.77	$3,819.03	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$55,262.80	$13,081,899.50
B2	929227M52	$9,988,000.00	$9,970,261.39	4.7175495788%	4.7175495788%	$39,196.00	$2,909.79	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$42,105.79	$9,967,351.60
B3	929227M60	$4,994,000.00	$4,985,130.71	4.7175495788%	4.7175495788%	$19,598.00	$1,454.90	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$21,052.90	$4,983,675.81
B4	929227M86	$1,872,000.00	$1,868,675.34	4.7175495788%	4.7175495788%	$7,346.31	$545.37	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$7,891.67	$1,868,129.97
B5	929227M94	$1,872,000.00	$1,868,675.34	4.7175495788%	4.7175495788%	$7,346.31	$545.37	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$7,891.67	$1,868,129.97
B6	929227N28	$3,124,477.61	$3,118,928.57	4.7175495788%	4.7175495788%	$12,261.42	$910.25	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$13,171.67	$3,118,018.32
R	929227M78	$100.00	$0.00	0.0000000000%	0.0000000000%	$0.36	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.36	$0.00
SFEE	XXXXXXXXX	$1,013,578,000.00	$749,544,822.58	0.3923972874%	0.3923972874%	$245,099.46	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$245,099.46	$691,032,564.60
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
Total		$1,248,537,577.61	$932,342,980.34			$3,665,312.22	$70,068,126.97	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$73,733,439.19	$862,274,853.37

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.03AR4
Distribution Date: 10/27/2003

Class	Orig Face	Beg Bal	Prin Loss	Prin Reimbursed	Subsequent Recoveries	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
A1	$249,500,000.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
A2	$115,300,000.00	$100,766,822.58	$0.00	$0.00	$0.00	$0.00	$58,512,257.98	0.3664749748	$42,254,564.60
A3	$170,000,000.00	$170,000,000.00	$0.00	$0.00	$0.00	$0.00	$0.00	1.0000000000	$170,000,000.00
A4	$123,700,000.00	$123,700,000.00	$0.00	$0.00	$0.00	$0.00	$0.00	1.0000000000	$123,700,000.00
A5	$110,200,000.00	$110,200,000.00	$0.00	$0.00	$0.00	$0.00	$0.00	1.0000000000	$110,200,000.00
A6	$244,878,000.00	$244,878,000.00	$0.00	$0.00	$0.00	$0.00	$0.00	1.0000000000	$244,878,000.00
A7	$200,000,000.00	$147,900,767.88	$0.00	$0.00	$0.00	$0.00	$11,545,684.29	0.6817754180	$136,355,083.59
X1	$1,013,578,000.00	$749,544,822.58	$0.00	$0.00	$0.00	$0.00	$0.00	0.6817754180	$691,032,564.60
X2	$200,000,000.00	$147,900,767.88	$0.00	$0.00	$0.00	$0.00	$0.00	0.6817754180	$136,355,083.59
B1	$13,109,000.00	$13,085,718.53	$0.00	$0.00	$0.00	$0.00	$3,819.03	0.9979326798	$13,081,899.50
B2	$9,988,000.00	$9,970,261.39	$0.00	$0.00	$0.00	$0.00	$2,909.79	0.9979326792	$9,967,351.60
B3	$4,994,000.00	$4,985,130.71	$0.00	$0.00	$0.00	$0.00	$1,454.90	0.9979326812	$4,983,675.81
B4	$1,872,000.00	$1,868,675.34	$0.00	$0.00	$0.00	$0.00	$545.37	0.9979326763	$1,868,129.97
B5	$1,872,000.00	$1,868,675.34	$0.00	$0.00	$0.00	$0.00	$545.37	0.9979326763	$1,868,129.97
B6	$3,124,477.61	$3,118,928.57	$0.00	$0.00	$0.00	$0.00	$910.25	0.9979326816	$3,118,018.32
R	$100.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
SFEE	$1,013,578,000.00	$749,544,822.58	$0.00	$0.00	$0.00	$0.00	$0.00	0.6817754180	$691,032,564.60
R_SYN	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
Total	$1,248,537,577.61	$932,342,980.34	$0.00	$0.00	$0.00	$0.00	$70,068,126.97	0.6906278744	$862,274,853.37

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.03AR4
Distribution Date: 10/27/2003
PER $1000 DENOMINATION
Class	Orig Face	Beg Bal	Prin Loss	Prin Reimbursed	Subsequent Recoveries	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
A1	$249,500,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
A2	$115,300,000.00	873.95336149	0.00000000	0.00000000	0.00000000	0.00000000	507.47838664	0.3664749748	366.47497485
A3	$170,000,000.00	1,000.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	1.0000000000	1,000.00000000
A4	$123,700,000.00	1,000.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	1.0000000000	1,000.00000000
A5	$110,200,000.00	1,000.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	1.0000000000	1,000.00000000
A6	$244,878,000.00	1,000.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	1.0000000000	1,000.00000000
A7	$200,000,000.00	739.50383940	0.00000000	0.00000000	0.00000000	0.00000000	57.72842145	0.6817754180	681.77541795
X1	$1,013,578,000.00	739.50383945	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.6817754180	681.77541797
X2	$200,000,000.00	739.50383940	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.6817754180	681.77541795
B1	$13,109,000.00	998.22400870	0.00000000	0.00000000	0.00000000	0.00000000	0.29132886	0.9979326798	997.93267984
B2	$9,988,000.00	998.22400781	0.00000000	0.00000000	0.00000000	0.00000000	0.29132859	0.9979326792	997.93267922
B3	$4,994,000.00	998.22401081	0.00000000	0.00000000	0.00000000	0.00000000	0.29132960	0.9979326812	997.93268122
B4	$1,872,000.00	998.22400641	0.00000000	0.00000000	0.00000000	0.00000000	0.29133013	0.9979326763	997.93267628
B5	$1,872,000.00	998.22400641	0.00000000	0.00000000	0.00000000	0.00000000	0.29133013	0.9979326763	997.93267628
B6	$3,124,477.61	998.22401032	0.00000000	0.00000000	0.00000000	0.00000000	0.29132870	0.9979326816	997.93268162
R	$100.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
SFEE	$1,013,578,000.00	739.50383945	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.6817754180	681.77541797
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: WAMU.03AR4
Distribution Date: 10/27/2003

Class	Orig Face	Int Rate Accrued	Int Rate Paid	Beg Cert Prin/Not Bal	Curent Int Accrued	Int Shortfall	Unscheduled Int	Int Reimbursed	Total Int Dist
A1	$249,500,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
A2	$115,300,000.00	2.2070000000%	2.2070000000%	$100,766,822.58	$185,326.98	$0.00	$0.00	$0.00	$185,326.98
A3	$170,000,000.00	2.8750000000%	2.8750000000%	$170,000,000.00	$407,291.67	$0.00	$0.00	$0.00	$407,291.67
A4	$123,700,000.00	3.3630000000%	3.3630000000%	$123,700,000.00	$346,669.25	$0.00	$0.00	$0.00	$346,669.25
A5	$110,200,000.00	3.5510000000%	3.5510000000%	$110,200,000.00	$326,100.17	$0.00	$0.00	$0.00	$326,100.17
A6	$244,878,000.00	3.4230000000%	3.4230000000%	$244,878,000.00	$698,514.50	$0.00	$0.00	$0.00	$698,514.50
A7	$200,000,000.00	3.9500000000%	3.9500000000%	$147,900,767.88	$486,840.03	$0.00	$0.00	$0.00	$486,840.03
X1	$1,013,578,000.00	1.1810000000%	1.1810000000%	$749,544,822.58	$737,677.03	$0.00	$0.00	$0.00	$737,677.03
X2	$200,000,000.00	0.7675495788%	0.7675495788%	$147,900,767.88	$94,600.98	$0.00	$0.00	$0.00	$94,600.98
B1	$13,109,000.00	4.7175495788%	4.7175495788%	$13,085,718.53	$51,443.77	$0.00	$0.00	$0.00	$51,443.77
B2	$9,988,000.00	4.7175495788%	4.7175495788%	$9,970,261.39	$39,196.00	$0.00	$0.00	$0.00	$39,196.00
B3	$4,994,000.00	4.7175495788%	4.7175495788%	$4,985,130.71	$19,598.00	$0.00	$0.00	$0.00	$19,598.00
B4	$1,872,000.00	4.7175495788%	4.7175495788%	$1,868,675.34	$7,346.31	$0.00	$0.00	$0.00	$7,346.31
B5	$1,872,000.00	4.7175495788%	4.7175495788%	$1,868,675.34	$7,346.31	$0.00	$0.00	$0.00	$7,346.31
B6	$3,124,477.61	4.7175495788%	4.7175495788%	$3,118,928.57	$12,261.42	$0.00	$0.00	$0.00	$12,261.42
R	$100.00	0.0000000000%	0.0000000000%	$0.00	$0.36	$0.00	$0.00	$0.00	$0.36
SFEE	$1,013,578,000.00	0.3923972874%	0.3923972874%	$749,544,822.58	$245,099.46	$0.00	$0.00	$0.00	$245,099.46
R_SYN	$0.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
Total	$1,248,537,577.61			$932,342,980.34	$3,665,312.22	$0.00	$0.00	$0.00	$3,665,312.22

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.03AR4
Distribution Date: 10/27/2003
PER $1000 DENOMINATION
Class	Orig Face	Int Rate Accrued	Int Rate Paid	Beg Cert Prin/Not Bal	Curent Int Accrued	Int Shortfall	Unscheduled Int	Int Reimbursed	Total Int Dist
A1	$249,500,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
A2	$115,300,000.00	2.2070000000%	2.2070000000%	873.95336149	1.60734588	0.00000000	0.00000000	0.00000000	1.60734588
A3	$170,000,000.00	2.8750000000%	2.8750000000%	1,000.00000000	2.39583335	0.00000000	0.00000000	0.00000000	2.39583335
A4	$123,700,000.00	3.3630000000%	3.3630000000%	1,000.00000000	2.80250000	0.00000000	0.00000000	0.00000000	2.80250000
A5	$110,200,000.00	3.5510000000%	3.5510000000%	1,000.00000000	2.95916670	0.00000000	0.00000000	0.00000000	2.95916670
A6	$244,878,000.00	3.4230000000%	3.4230000000%	1,000.00000000	2.85250002	0.00000000	0.00000000	0.00000000	2.85250002
A7	$200,000,000.00	3.9500000000%	3.9500000000%	739.50383940	2.43420015	0.00000000	0.00000000	0.00000000	2.43420015
X1	$1,013,578,000.00	1.1810000000%	1.1810000000%	739.50383945	0.72779503	0.00000000	0.00000000	0.00000000	0.72779503
X2	$200,000,000.00	0.7675495788%	0.7675495788%	739.50383940	0.47300490	0.00000000	0.00000000	0.00000000	0.47300490
B1	$13,109,000.00	4.7175495788%	4.7175495788%	998.22400870	3.92430925	0.00000000	0.00000000	0.00000000	3.92430925
B2	$9,988,000.00	4.7175495788%	4.7175495788%	998.22400781	3.92430917	0.00000000	0.00000000	0.00000000	3.92430917
B3	$4,994,000.00	4.7175495788%	4.7175495788%	998.22401081	3.92430917	0.00000000	0.00000000	0.00000000	3.92430917
B4	$1,872,000.00	4.7175495788%	4.7175495788%	998.22400641	3.92431090	0.00000000	0.00000000	0.00000000	3.92431090
B5	$1,872,000.00	4.7175495788%	4.7175495788%	998.22400641	3.92431090	0.00000000	0.00000000	0.00000000	3.92431090
B6	$3,124,477.61	4.7175495788%	4.7175495788%	998.22401032	3.92431041	0.00000000	0.00000000	0.00000000	3.92431041
R	$100.00	0.0000000000%	0.0000000000%	0.00000000	3.60000000	0.00000000	0.00000000	0.00000000	3.60000000
SFEE	$1,013,578,000.00	0.3923972874%	0.3923972874%	739.50383945	0.24181608	0.00000000	0.00000000	0.00000000	0.24181608
R_SYN	$0.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
10/2003 DISTRIBUTION REPORT
SERIES: WAMU 03AR4
WEIGHTED AVERAGE PC RATE: 4.71755%
WEIGHTED AVERAGE MATURITY: 221.25906
WEIGHTED AVERAGE LOAN AGE: 7.33873
POOL NUMBER: 2064
ISSUE DATE: 03/21/2003
CERTIFICATE BALANCE AT ISSUE: $1,248,537,577.61
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	1580		$932,342,980.35
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$272,101.46
Unscheduled Principal Collection/Reversals		$642,991.60
Liquidations-in-full	107	$69,153,033.91
Subsequent Recoveries		$0.00
Net principal Distributed		$70,068,126.97	-$70,068,126.97

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	1473		$862,274,853.38

SCHEDULED INTEREST AT MORTGAGE RATE:		$4,053,788.59

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
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
10/2003 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$388,476.37

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:		$73,733,439.19

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
10/2003 DISTRIBUTION REPORT
SERIES: WAMU 03AR4
WEIGHTED AVERAGE PC RATE: 4.71755%
WEIGHTED AVERAGE MATURITY: 221.25906
WEIGHTED AVERAGE LOAN AGE: 7.33873
POOL NUMBER: ALL
ISSUE DATE: 03/21/2003
CERTIFICATE BALANCE AT ISSUE: $1,248,537,577.61
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	1580		$932,342,980.35
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$272,101.46
Unscheduled Principal Collection/Reversals		$642,991.60
Liquidations-in-full	107	$69,153,033.91
Subsequent Recoveries		$0.00
Net principal Distributed		$70,068,126.97	-$70,068,126.97

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	1473		$862,274,853.38

SCHEDULED INTEREST AT MORTGAGE RATE:		$4,053,788.59

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
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
10/2003 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$388,476.37

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:		$73,733,439.19

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.03AR4
Distribution Date: 10/27/2003

Distribution by Group
Pool ID		Principal		Interest		Total
Pool - 2064		$70,068,126.97		$3,665,312.22		$73,733,439.19
Aggregate		$70,068,126.97		$3,665,312.22		$73,733,439.19

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 - 2064	$932,342,980.35	1580	107	1473	$862,274,853.38	$272,101.46	$69,153,033.91	$642,991.60	$70,068,126.97
Aggregate	$932,342,980.35	1580	107	1473	$862,274,853.38	$272,101.46	$69,153,033.91	$642,991.60	$70,068,126.97

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 - 2064	11	$6,388,517.99	0	$0.00	0	$0.00	0	$0.00
Aggregate	11	$6,388,517.99	0	$0.00	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 - 2064		0		$0.00		0		$0.00
Aggregate		0		$0.00		0		$0.00

Aggregate Loss Amounts by Group
Pool ID			Count			Loss Amount
Group 1(2064)			0			$0.00
Aggregate			0			$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.03AR4
Distribution Date: 10/27/2003

INSURANCE RESERVES - Group 1(2064)
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	$16,927,800.00	$0.00	$0.00	$0.00	$16,927,800.00
Bankruptcy Bond
Single-Units	$136,209.00	$0.00	$0.00	$0.00	$136,209.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$24,970,752.00	$0.00	$0.00	$0.00	$24,970,752.00

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	$16,927,800.00	$0.00	$0.00	$0.00	$16,927,800.00
Bankruptcy Bond
Single-Units	$136,209.00	$0.00	$0.00	$0.00	$136,209.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$24,970,752.00	$0.00	$0.00	$0.00	$24,970,752.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.03AR4
Distribution Date: 10/27/2003

The Class Principal Balances of each Class of the Class B1,B2,B3,B4,B5,B6 Certificatesimmediately after the principal and interest distribution on 200310 are as follows:

Class			Class Principal Balance
B1			$13,081,899.50
B2			$9,967,351.60
B3			$4,983,675.81
B4			$1,868,129.97
B5			$1,868,129.97
B6			$3,118,018.32
Total			$34,887,205.18
Capitalized items used but not defined herein have the meanings ascribed to them in the Prospectus Supplement.

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.03AR4
Distribution Date: 10/27/2003

Aggregate ARM Information by Group
Pool ID	Netwac	Margin
Pool - 2064	4.71755%	2.25019%
Aggregate	4.71755%	2.25002%

WAMU MORTGAGE PASS THROUGH CERTIFICATES SERIES 2003-AR4 8-K