WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WMMSC.012
Distribution Date: 12/26/2003

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
A1V	939335AA3	$381,550,000.00	$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
A1F	939335AB1	$28,200,000.00	$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	939335AC9	$260,300,000.00	$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
A3	939335AD7	$262,400,000.00	$28,310,926.05	6.0100000000%	6.0100000000%	$141,790.55	$1,708,447.36	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$1,850,237.91	$26,602,478.69
X	939335AE5	$954,304,000.00	$35,128,148.39	1.1753098199%	1.1753098199%	$34,405.38	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$34,405.38	$33,250,270.33
B1	939335AF2	$12,141,000.00	$3,787,311.08	6.3500000000%	6.3500000000%	$20,041.19	$94,127.31	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$114,168.49	$3,693,183.77
B2	939335AG0	$9,713,000.00	$3,029,911.26	6.4400000000%	6.4400000000%	$16,260.52	$75,303.40	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$91,563.92	$2,954,607.86
B3	939335AH8	$6,313,000.00	$1,969,301.94	7.2590554549%	7.2590554549%	$11,912.73	$48,943.72	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$60,856.44	$1,920,358.22
R1	939335AJ4	$50.00	$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
R2	939335AK1	$50.00	$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
B4	939335AL9	$5,342,000.00	$1,666,404.41	7.2590554549%	7.2590554549%	$10,080.44	$41,415.70	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$51,496.14	$1,624,988.71
B5	939335AM7	$2,428,000.00	$757,399.83	7.2590554549%	7.2590554549%	$4,581.67	$18,823.91	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$23,405.58	$738,575.92
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
B6	939335AN5	$2,913,968.00	$908,994.67	7.2590554549%	7.2590554549%	$5,498.70	$22,591.51	$0.00	$0.03	$0.00	$0.00	$0.00	$0.00	$0.00	$28,090.22	$886,403.12
Total		$971,301,068.00	$40,430,249.24			$244,571.18	$2,009,652.91	$0.00	$0.03	$0.00	$0.00	$0.00	$0.00	$0.00	$2,254,224.09	$38,420,596.30

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WMMSC.012
Distribution Date: 12/26/2003

Class	Orig Face	Beg Bal	Prin Loss	Prin Reimbursed	Subsequent Recoveries	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
A1V	$381,550,000.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
A1F	$28,200,000.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
A2	$260,300,000.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
A3	$262,400,000.00	$28,310,926.05	$0.00	$0.00	$0.00	$0.00	$1,708,447.36	0.1013813974	$26,602,478.69
X	$954,304,000.00	$35,128,148.39	$0.00	$0.00	$0.00	$0.00	$0.00	0.0348424300	$33,250,270.33
B1	$12,141,000.00	$3,787,311.08	$0.00	$0.00	$0.00	$0.00	$94,127.31	0.3041910691	$3,693,183.77
B2	$9,713,000.00	$3,029,911.26	$0.00	$0.00	$0.00	$0.00	$75,303.40	0.3041910697	$2,954,607.86
B3	$6,313,000.00	$1,969,301.94	$0.00	$0.00	$0.00	$0.00	$48,943.72	0.3041910692	$1,920,358.22
R1	$50.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
R2	$50.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
B4	$5,342,000.00	$1,666,404.41	$0.00	$0.00	$0.00	$0.00	$41,415.70	0.3041910726	$1,624,988.71
B5	$2,428,000.00	$757,399.83	$0.00	$0.00	$0.00	$0.00	$18,823.91	0.3041910708	$738,575.92
R_SYN	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
B6	$2,913,968.00	$908,994.67	$0.03	$0.00	$0.00	$0.00	$22,591.51	0.3041910961	$886,403.12
Total	$971,301,068.00	$40,430,249.24	$0.03	$0.00	$0.00	$0.00	$2,009,652.91	0.0395558057	$38,420,596.30

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WMMSC.012
Distribution Date: 12/26/2003
PER $1000 DENOMINATION
Class	Orig Face	Beg Bal	Prin Loss	Prin Reimbursed	Subsequent Recoveries	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
A1V	$381,550,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
A1F	$28,200,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
A2	$260,300,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
A3	$262,400,000.00	107.89224867	0.00000000	0.00000000	0.00000000	0.00000000	6.51085122	0.1013813974	101.38139745
X	$954,304,000.00	36.81022860	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0348424300	34.84243001
B1	$12,141,000.00	311.94391566	0.00000000	0.00000000	0.00000000	0.00000000	7.75284655	0.3041910691	304.19106910
B2	$9,713,000.00	311.94391640	0.00000000	0.00000000	0.00000000	0.00000000	7.75284670	0.3041910697	304.19106970
B3	$6,313,000.00	311.94391573	0.00000000	0.00000000	0.00000000	0.00000000	7.75284651	0.3041910692	304.19106922
R1	$50.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
R2	$50.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
B4	$5,342,000.00	311.94391801	0.00000000	0.00000000	0.00000000	0.00000000	7.75284538	0.3041910726	304.19107263
B5	$2,428,000.00	311.94391680	0.00000000	0.00000000	0.00000000	0.00000000	7.75284596	0.3041910708	304.19107084
R_SYN	$0.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
B6	$2,913,968.00	311.94394379	0.00001030	0.00000000	0.00000000	0.00000000	7.75283394	0.3041910961	304.19109613

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WMMSC.012
Distribution Date: 12/26/2003

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
A1V	$381,550,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
A1F	$28,200,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
A2	$260,300,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
A3	$262,400,000.00	6.0100000000%	6.0100000000%	$28,310,926.05	$141,790.55	$0.00	$0.00	$0.00	$141,790.55
X	$954,304,000.00	1.1753098199%	1.1753098199%	$35,128,148.39	$34,405.38	$0.00	$0.00	$0.00	$34,405.38
B1	$12,141,000.00	6.3500000000%	6.3500000000%	$3,787,311.08	$20,041.19	$0.00	$0.00	$0.00	$20,041.19
B2	$9,713,000.00	6.4400000000%	6.4400000000%	$3,029,911.26	$16,260.52	$0.00	$0.00	$0.00	$16,260.52
B3	$6,313,000.00	7.2590554549%	7.2590554549%	$1,969,301.94	$11,912.73	$0.00	$0.00	$0.00	$11,912.73
R1	$50.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
R2	$50.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
B4	$5,342,000.00	7.2590554549%	7.2590554549%	$1,666,404.41	$10,080.44	$0.00	$0.00	$0.00	$10,080.44
B5	$2,428,000.00	7.2590554549%	7.2590554549%	$757,399.83	$4,581.67	$0.00	$0.00	$0.00	$4,581.67
R_SYN	$0.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
B6	$2,913,968.00	7.2590554549%	7.2590554549%	$908,994.67	$5,498.70	$0.00	$0.00	$0.00	$5,498.70
Total	$971,301,068.00			$40,430,249.24	$244,571.18	$0.00	$0.00	$0.00	$244,571.18

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WMMSC.012
Distribution Date: 12/26/2003
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
A1V	$381,550,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
A1F	$28,200,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
A2	$260,300,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
A3	$262,400,000.00	6.0100000000%	6.0100000000%	107.89224867	0.54036033	0.00000000	0.00000000	0.00000000	0.54036033
X	$954,304,000.00	1.1753098199%	1.1753098199%	36.81022860	0.03605285	0.00000000	0.00000000	0.00000000	0.03605285
B1	$12,141,000.00	6.3500000000%	6.3500000000%	311.94391566	1.65070340	0.00000000	0.00000000	0.00000000	1.65070340
B2	$9,713,000.00	6.4400000000%	6.4400000000%	311.94391640	1.67409863	0.00000000	0.00000000	0.00000000	1.67409863
B3	$6,313,000.00	7.2590554549%	7.2590554549%	311.94391573	1.88701568	0.00000000	0.00000000	0.00000000	1.88701568
R1	$50.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
R2	$50.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
B4	$5,342,000.00	7.2590554549%	7.2590554549%	311.94391801	1.88701610	0.00000000	0.00000000	0.00000000	1.88701610
B5	$2,428,000.00	7.2590554549%	7.2590554549%	311.94391680	1.88701400	0.00000000	0.00000000	0.00000000	1.88701400
R_SYN	$0.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
B6	$2,913,968.00	7.2590554549%	7.2590554549%	311.94394379	1.88701455	0.00000000	0.00000000	0.00000000	1.88701455

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
12/2003 DISTRIBUTION REPORT
SERIES: WMMSC 012
WEIGHTED AVERAGE PC RATE: 7.25906%
WEIGHTED AVERAGE MATURITY: 270.62631
WEIGHTED AVERAGE LOAN AGE: 58.09082
POOL NUMBER: 1699
ISSUE DATE: 03/28/2001
CERTIFICATE BALANCE AT ISSUE: $971,301,068.00
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	179		$40,430,249.24
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$56,581.24
Unscheduled Principal Collection/Reversals		$23,669.63
Liquidations-in-full	9	$1,929,402.07
Subsequent Recoveries		$0.00
Net principal Distributed		$2,009,652.94	-$2,009,652.94

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	170		$38,420,596.30

SCHEDULED INTEREST AT MORTGAGE RATE:		$254,678.74

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
12/2003 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$10,107.59

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:		$2,254,224.09

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
12/2003 DISTRIBUTION REPORT
SERIES: WMMSC 012
WEIGHTED AVERAGE PC RATE: 7.25906%
WEIGHTED AVERAGE MATURITY: 270.62631
WEIGHTED AVERAGE LOAN AGE: 58.09082
POOL NUMBER: ALL
ISSUE DATE: 03/28/2001
CERTIFICATE BALANCE AT ISSUE: $971,301,068.00
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	179		$40,430,249.24
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$56,581.24
Unscheduled Principal Collection/Reversals		$23,669.63
Liquidations-in-full	9	$1,929,402.07
Subsequent Recoveries		$0.00
Net principal Distributed		$2,009,652.94	-$2,009,652.94

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	170		$38,420,596.30

SCHEDULED INTEREST AT MORTGAGE RATE:		$254,678.74

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
12/2003 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$10,107.59

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:		$2,254,224.09

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WMMSC.012
Distribution Date: 12/26/2003

Distribution by Group
Pool ID		Principal		Interest		Total
Pool - 1699		$2,009,652.94		$244,571.15		$2,254,224.09
Aggregate		$2,009,652.94		$244,571.15		$2,254,224.09

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 - 1699	$40,430,249.24	179	9	170	$38,420,596.30	$56,581.24	$1,929,402.07	$23,669.63	$2,009,652.94
Aggregate	$40,430,249.24	179	9	170	$38,420,596.30	$56,581.24	$1,929,402.07	$23,669.63	$2,009,652.94

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 - 1699	7	$1,655,669.37	0	$0.00	1	$520,090.62	0	$0.00
Aggregate	7	$1,655,669.37	0	$0.00	1	$520,090.62	0	$0.00

Foreclosure and REO Information by Group
Pool ID		Foreclosure Count		Sched End Balance		REO Count		Sched End Balance
Pool - 1699		3		$651,370.61		1		$999,813.33
Aggregate		3		$651,370.61		1		$999,813.33

Aggregate Loss Amounts by Group
Pool ID			Count			Loss Amount
Group 1(1699)			0			$0.00
Aggregate			0			$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WMMSC.012
Distribution Date: 12/26/2003

INSURANCE RESERVES - Group 1(1699)
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	$11,031,626.00	$0.00	$0.00	$0.00	$11,031,626.00
Bankruptcy Bond
Single-Units	$223,800.00	$0.00	$0.00	$0.00	$223,800.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$9,606,171.00	$0.00	$0.00	$0.00	$9,606,171.00

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	$11,031,626.00	$0.00	$0.00	$0.00	$11,031,626.00
Bankruptcy Bond
Single-Units	$223,800.00	$0.00	$0.00	$0.00	$223,800.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$9,606,171.00	$0.00	$0.00	$0.00	$9,606,171.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WMMSC.012
Distribution Date: 12/26/2003

The Class Principal Balances of each Class of the Class B1,B2,B3,B4,B5,B6 Certificatesimmediately after the principal and interest distribution on 200312 are as follows:

Class			Class Principal Balance
B1			$3,693,183.77
B2			$2,954,607.86
B3			$1,920,358.22
B4			$1,624,988.71
B5			$738,575.92
B6			$886,403.12
Total			$11,818,117.61
Capitalized items used but not defined herein have the meanings ascribed to them in the Prospectus Supplement.

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WMMSC.012
Distribution Date: 12/26/2003

Aggregate ARM Information by Group
Pool ID	Netwac	Margin
Pool - 1699	7.25906%	2.44738%
Aggregate	7.25906%	2.44750%

PNC MORTGAGE SEC CORP MORT PASS THR CERT SER 2001-2 8-K