WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03MS1
Distribution Date: 12/27/2004

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	939336PZ0	$139,234,198.00	$28,240,015.89	5.0000000000%	5.0000000000%	$117,666.73	$1,180,849.80	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$1,298,516.53	$27,059,166.09
IIA	939336QA4	$100,089,753.00	$33,204,806.11	5.2500000000%	5.2500000000%	$145,271.03	$871,874.72	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$1,017,145.75	$32,332,931.39
CX	939336QB2	$22,222,325.00	$3,978,370.84	5.0000000000%	4.9999999975%	$16,576.55	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$16,576.55	$3,754,486.16
CP	939336QC0	$196,266.29	$115,520.31	0.0000000000%	0.0000000000%	$0.00	$716.61	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$716.61	$114,803.70
CB1	939336QD8	$1,576,590.00	$1,438,534.40	5.1048616442%	5.1048616442%	$6,119.60	$6,670.33	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$12,789.93	$1,431,864.07
CB2	939336QE6	$485,104.00	$442,625.40	5.1048616442%	5.1048616442%	$1,882.95	$2,052.41	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$3,935.36	$440,572.99
CB3	939336QF3	$363,828.00	$331,969.06	5.1048616442%	5.1048616442%	$1,412.21	$1,539.30	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$2,951.52	$330,429.76
CB4	939336QH9	$121,276.00	$110,656.37	5.1048616442%	5.1048616442%	$470.74	$513.10	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$983.84	$110,143.27
CB5	939336QJ5	$242,552.00	$221,312.68	5.1048616442%	5.1048616442%	$941.48	$1,026.20	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$1,967.68	$220,286.48
CB6	939336QK2	$242,553.79	$221,414.20	5.1048616442%	5.1048616442%	$941.91	$1,026.21	$0.00	$0.00	$0.00	$0.47	$0.00	$0.00	$0.00	$0.00	$0.00	$1,968.12	$220,387.52
R	939336QG1	$100.00	$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
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		$242,552,221.08	$64,326,854.42			$291,283.19	$2,066,268.69	$0.00	$0.00	$0.00	$0.47	$0.00	$0.00	$0.00	$0.00	$0.00	$2,357,551.88	$62,260,585.26

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03MS1
Distribution Date: 12/27/2004

Class	Orig Face	Beg Bal	Prin Loss	Prin Reimbursed	Subsequent Recoveries	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
IA	$139,234,198.00	$28,240,015.89	$0.00	$0.00	$0.00	$0.00	$1,180,849.80	0.1943428158	$27,059,166.09
IIA	$100,089,753.00	$33,204,806.11	$0.00	$0.00	$0.00	$0.00	$871,874.72	0.3230393764	$32,332,931.39
CX	$22,222,325.00	$3,978,370.84	$0.00	$0.00	$0.00	$0.00	$0.00	0.1689510958	$3,754,486.16
CP	$196,266.29	$115,520.31	$0.00	$0.00	$0.00	$0.00	$716.61	0.5849384528	$114,803.70
CB1	$1,576,590.00	$1,438,534.40	$0.00	$0.00	$0.00	$0.00	$6,670.33	0.9082031917	$1,431,864.07
CB2	$485,104.00	$442,625.40	$0.00	$0.00	$0.00	$0.00	$2,052.41	0.9082031688	$440,572.99
CB3	$363,828.00	$331,969.06	$0.00	$0.00	$0.00	$0.00	$1,539.30	0.9082032169	$330,429.76
CB4	$121,276.00	$110,656.37	$0.00	$0.00	$0.00	$0.00	$513.10	0.9082033543	$110,143.27
CB5	$242,552.00	$221,312.68	$0.00	$0.00	$0.00	$0.00	$1,026.20	0.9082031070	$220,286.48
CB6	$242,553.79	$221,414.20	$0.47	$0.00	$0.00	$0.00	$1,026.21	0.9086129720	$220,387.52
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	$242,552,221.08	$64,326,854.42	$0.47	$0.00	$0.00	$0.00	$2,066,268.69	0.2566894048	$62,260,585.26

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03MS1
Distribution Date: 12/27/2004
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	$139,234,198.00	202.82384856	0.00000000	0.00000000	0.00000000	0.00000000	8.48103280	0.1943428158	194.34281576
IIA	$100,089,753.00	331.75030525	0.00000000	0.00000000	0.00000000	0.00000000	8.71092888	0.3230393764	323.03937637
CX	$22,222,325.00	179.02585981	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.1689510958	168.95109580
CP	$196,266.29	588.58966560	0.00000000	0.00000000	0.00000000	0.00000000	3.65121285	0.5849384528	584.93845275
CB1	$1,576,590.00	912.43405070	0.00000000	0.00000000	0.00000000	0.00000000	4.23085901	0.9082031917	908.20319170
CB2	$485,104.00	912.43403476	0.00000000	0.00000000	0.00000000	0.00000000	4.23086596	0.9082031688	908.20316881
CB3	$363,828.00	912.43406225	0.00000000	0.00000000	0.00000000	0.00000000	4.23084534	0.9082032169	908.20321690
CB4	$121,276.00	912.43419968	0.00000000	0.00000000	0.00000000	0.00000000	4.23084534	0.9082033543	908.20335433
CB5	$242,552.00	912.43395231	0.00000000	0.00000000	0.00000000	0.00000000	4.23084534	0.9082031070	908.20310696
CB6	$242,553.79	912.84576506	0.00193771	0.00000000	0.00000000	0.00000000	4.23085535	0.9086129720	908.61297199
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.03MS1
Distribution Date: 12/27/2004

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	$139,234,198.00	5.0000000000%	5.0000000000%	$28,240,015.89	$117,666.73	$0.00	$0.00	$0.00	$0.00	$0.00	$117,666.73
IIA	$100,089,753.00	5.2500000000%	5.2500000000%	$33,204,806.11	$145,271.03	$0.00	$0.00	$0.00	$0.00	$0.00	$145,271.03
CX	$22,222,325.00	5.0000000000%	4.9999999975%	$3,978,370.84	$16,576.55	$0.00	$0.00	$0.00	$0.00	$0.00	$16,576.55
CP	$196,266.29	0.0000000000%	0.0000000000%	$115,520.31	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
CB1	$1,576,590.00	5.1048616442%	5.1048616442%	$1,438,534.40	$6,119.60	$0.00	$0.00	$0.00	$0.00	$0.00	$6,119.60
CB2	$485,104.00	5.1048616442%	5.1048616442%	$442,625.40	$1,882.95	$0.00	$0.00	$0.00	$0.00	$0.00	$1,882.95
CB3	$363,828.00	5.1048616442%	5.1048616442%	$331,969.06	$1,412.21	$0.00	$0.00	$0.00	$0.00	$0.00	$1,412.21
CB4	$121,276.00	5.1048616442%	5.1048616442%	$110,656.37	$470.74	$0.00	$0.00	$0.00	$0.00	$0.00	$470.74
CB5	$242,552.00	5.1048616442%	5.1048616442%	$221,312.68	$941.48	$0.00	$0.00	$0.00	$0.00	$0.00	$941.48
CB6	$242,553.79	5.1048616442%	5.1048616442%	$221,414.20	$941.91	$0.00	$0.00	$0.00	$0.00	$0.00	$941.91
R	$100.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
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	$242,552,221.08			$64,326,854.42	$291,283.19	$0.00	$0.00	$0.00	$0.00	$0.00	$291,283.19

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03MS1
Distribution Date: 12/27/2004
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	$139,234,198.00	5.0000000000%	5.0000000000%	202.82384856	0.84509935	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.84509935
IIA	$100,089,753.00	5.2500000000%	5.2500000000%	331.75030525	1.45140762	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	1.45140762
CX	$22,222,325.00	5.0000000000%	4.9999999975%	179.02585981	0.74594130	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.74594130
CP	$196,266.29	0.0000000000%	0.0000000000%	588.58966560	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
CB1	$1,576,590.00	5.1048616442%	5.1048616442%	912.43405070	3.88154181	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.88154181
CB2	$485,104.00	5.1048616442%	5.1048616442%	912.43403476	3.88153880	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.88153880
CB3	$363,828.00	5.1048616442%	5.1048616442%	912.43406225	3.88153193	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.88153193
CB4	$121,276.00	5.1048616442%	5.1048616442%	912.43419968	3.88155942	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.88155942
CB5	$242,552.00	5.1048616442%	5.1048616442%	912.43395231	3.88155942	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.88155942
CB6	$242,553.79	5.1048616442%	5.1048616442%	912.84576506	3.88330358	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.88330358
R	$100.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
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
12/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03MS1
WEIGHTED AVERAGE PC RATE: 5.57448%
WEIGHTED AVERAGE MATURITY: 146.15132
WEIGHTED AVERAGE LOAN AGE: 30.42900
POOL NUMBER: 2021
ISSUE DATE: 01/31/2003
CERTIFICATE BALANCE AT ISSUE: $141,021,215.25
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	79		$29,864,658.17
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$141,343.58
Unscheduled Principal Collection/Reversals		$40,319.12
Liquidations-in-full	3	$1,006,875.90
Subsequent Recoveries		$0.00
Net principal Distributed		$1,188,538.60	-$1,188,538.60

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	76		$28,676,119.57

SCHEDULED INTEREST AT MORTGAGE RATE:		$147,578.83

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
12/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$8,845.50

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:		$1,327,271.93

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
12/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03MS1
WEIGHTED AVERAGE PC RATE: 5.31189%
WEIGHTED AVERAGE MATURITY: 150.32067
WEIGHTED AVERAGE LOAN AGE: 24.81243
POOL NUMBER: 2022
ISSUE DATE: 01/31/2003
CERTIFICATE BALANCE AT ISSUE: $101,531,005.83
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	90		$34,462,196.24
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$155,246.69
Unscheduled Principal Collection/Reversals		$127,735.93
Liquidations-in-full	1	$594,747.93
Subsequent Recoveries		$0.00
Net principal Distributed		$877,730.55	-$877,730.55

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	89		$33,584,465.69

SCHEDULED INTEREST AT MORTGAGE RATE:		$166,403.49

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
12/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$13,854.09

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:		$1,030,279.95

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
12/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03MS1
WEIGHTED AVERAGE PC RATE: 5.43380%
WEIGHTED AVERAGE MATURITY: 148.40034
WEIGHTED AVERAGE LOAN AGE: 27.39932
POOL NUMBER: Group 1
ISSUE DATE: 01/31/2003
CERTIFICATE BALANCE AT ISSUE: $242,552,221.08
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	169		$64,326,854.41
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$296,590.27
Unscheduled Principal Collection/Reversals		$168,055.05
Liquidations-in-full	4	$1,601,623.83
Subsequent Recoveries		$0.00
Net principal Distributed		$2,066,269.15	-$2,066,269.15

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	165		$62,260,585.26

SCHEDULED INTEREST AT MORTGAGE RATE:		$313,982.32

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
12/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$22,699.59

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:		$2,357,551.88

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
12/2004 DISTRIBUTION REPORT
SERIES: WAMMS 03MS1
WEIGHTED AVERAGE PC RATE: 5.43380%
WEIGHTED AVERAGE MATURITY: 148.40034
WEIGHTED AVERAGE LOAN AGE: 27.39932
POOL NUMBER: ALL
ISSUE DATE: 01/31/2003
CERTIFICATE BALANCE AT ISSUE: $242,552,221.08
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	169		$64,326,854.41
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$296,590.27
Unscheduled Principal Collection/Reversals		$168,055.05
Liquidations-in-full	4	$1,601,623.83
Subsequent Recoveries		$0.00
Net principal Distributed		$2,066,269.15	-$2,066,269.15

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	165		$62,260,585.26

SCHEDULED INTEREST AT MORTGAGE RATE:		$313,982.32

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
12/2004 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$22,699.59

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:		$2,357,551.88

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03MS1
Distribution Date: 12/27/2004

Distribution by Group
Pool ID		Principal		Interest		Total
Pool - 2021		$1,188,538.60		$138,733.33		$1,327,271.93
Pool - 2022		$877,730.55		$152,549.40		$1,030,279.95
Group 1		$2,066,269.15		$291,282.73		$2,357,551.88
Aggregate		$2,066,269.15		$291,282.73		$2,357,551.88

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 - 2021	$29,864,658.17	79	3	76	$28,676,119.57	$141,343.58	$1,006,875.90	$40,319.12	$1,188,538.60
Pool - 2022	$34,462,196.24	90	1	89	$33,584,465.69	$155,246.69	$594,747.93	$127,735.93	$877,730.55
Group 1	$64,326,854.41	169	4	165	$62,260,585.26	$296,590.27	$1,601,623.83	$168,055.05	$2,066,269.15
Aggregate	$64,326,854.41	169	4	165	$62,260,585.26	$296,590.27	$1,601,623.83	$168,055.05	$2,066,269.15

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 - 2021	1	$336,500.47	0	$0.00	0	$0.00	0	$0.00
Pool - 2022	0	$0.00	0	$0.00	0	$0.00	0	$0.00
Group 1	1	$336,500.47	0	$0.00	0	$0.00	0	$0.00
Aggregate	1	$336,500.47	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 - 2021		0		$0.00		0		$0.00
Pool - 2022		0		$0.00		0		$0.00
Group 1		0		$0.00		0		$0.00
Aggregate		0		$0.00		0		$0.00

Aggregate Loss Amounts by Group
Pool ID			Count			Loss Amount
Pool - 2021			0			$0.00
Pool - 2022			0			$0.00
Group 1			0			$0.00
Aggregate			0			$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03MS1
Distribution Date: 12/27/2004

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	$4,054,992.00	$0.00	$0.00	$0.00	$4,054,992.00
Bankruptcy Bond
Single-Units	$100,000.00	$0.00	$0.00	$0.00	$100,000.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$2,425,522.00	$0.00	$0.00	$0.00	$2,425,522.00

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	$4,054,992.00	$0.00	$0.00	$0.00	$4,054,992.00
Bankruptcy Bond
Single-Units	$100,000.00	$0.00	$0.00	$0.00	$100,000.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$2,425,522.00	$0.00	$0.00	$0.00	$2,425,522.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMMS.03MS1
Distribution Date: 12/27/2004

The Group C-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 and II Certificates. The "Prospectus Supplement" is that certain Prospectus Supplement, dated January 27, 2003 to that certain Prospectus Supplement, dated November 21, 2002, to which certain Group I and II Certificates were offered. The Special Hazard, Bankruptcy, and Fraud coverage (collectively, "Credit Enhancements") provided by the C-B certificates provide coverage to the Group I and II Loans, subject to the conditions and limitations to payment specified thereunder.



The Class Principal Balances of each Class of the Class CB1,CB2,CB3,CB4,CB5,CB6 Certificatesimmediately after the principal and interest distribution on 200412 are as follows:

Class			Class Principal Balance
CB1			$1,431,864.07
CB2			$440,572.99
CB3			$330,429.76
CB4			$110,143.27
CB5			$220,286.48
CB6			$220,387.52
Total			$2,753,684.08
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 $4,054,992.00, $100,000.00, $2,425,522.00 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."

WASHINGTON MUTUAL MORT SEC CORP PAS THR CERTS SER 2003 MS1 8-K