WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003

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	Total Dist	Ending Class Bal
IA1	929227JX5	$20,000,000.00	$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
IA2	929227JY3	$28,090,000.00	$6,746,044.32	6.5000000000%	6.5000000000%	$36,541.07	$6,746,044.32	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$6,782,585.39	$0.00
IA3	929227JZ0	$32,828,000.00	$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
IA4	929227KA3	$33,000,000.00	$36,370,006.90	6.5000000000%	6.5000000000%	$197,004.20	$19,097,395.73	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$19,294,399.93	$17,272,611.17
IA5	929227KB1	$52,000,000.00	$52,000,000.00	6.5000000000%	6.5000000000%	$281,666.67	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$281,666.67	$52,000,000.00
IA6	929227KC9	$65,000,000.00	$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
IA7	929227KD7	$65,000,000.00	$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
IA8	929227KE5	$60,000,000.00	$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
IA9	929227KF2	$60,000,000.00	$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
IA10	929227KG0	$39,758,000.00	$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
IA11	929227KH8	$4,969,750.00	$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
IA12	929227KJ4	$35,242,000.00	$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
IA13	929227KK1	$35,000,000.00	$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
IIA1	929227KL9	$33,111,000.00	$6,238,735.38	6.5000000000%	6.5000000000%	$33,793.15	$395,204.41	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$428,997.56	$5,843,530.97
IIIA1	929227KM7	$120,784,000.00	$27,581,793.31	6.0000000000%	6.0000000000%	$137,908.97	$4,965,037.80	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$5,102,946.77	$22,616,755.51
IP	929227KN5	$2,806,046.00	$1,230,982.41	0.0000000000%	0.0000000000%	$0.00	$310,830.62	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$310,830.62	$920,151.79
IIP	929227KP0	$188,195.00	$83,726.62	0.0000000000%	0.0000000000%	$0.00	$15,606.14	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$15,606.14	$68,120.48
IIIP	929227KQ8	$635,611.00	$374,080.84	0.0000000000%	0.0000000000%	$0.00	$59,941.93	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$59,941.93	$314,138.91
IIIB1	929227KU9	$369,000.00	$345,316.20	6.0000000000%	6.0000000000%	$1,726.58	$1,399.31	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$3,125.89	$343,916.89
IIIB2	929227KV7	$246,000.00	$230,210.80	6.0000000000%	6.0000000000%	$1,151.05	$932.87	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$2,083.93	$229,277.93
IIIB3	929227KW5	$493,000.00	$461,357.43	6.0000000000%	6.0000000000%	$2,306.79	$1,869.54	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$4,176.32	$459,487.89
IIIB4	929227LB0	$369,000.00	$345,316.20	6.0000000000%	6.0000000000%	$1,726.58	$1,399.31	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$3,125.89	$343,916.89
IIIB5	929227LC8	$184,000.00	$172,190.17	6.0000000000%	6.0000000000%	$860.95	$697.76	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$1,558.71	$171,492.41
IIIB6	929227LD6	$188,205.00	$176,125.51	6.0000000000%	6.0000000000%	$880.63	$713.70	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$1,594.33	$175,411.81
CB1	929227KR6	$7,161,000.00	$7,042,996.43	6.5000000000%	6.5000000000%	$38,149.56	$6,985.67	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$45,135.24	$7,036,010.76
CB2	929227KS4	$2,813,000.00	$2,766,645.56	6.5000000000%	6.5000000000%	$14,986.00	$2,744.13	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$17,730.12	$2,763,901.43
CB3	929227KT2	$2,046,000.00	$2,012,284.69	6.5000000000%	6.5000000000%	$10,899.88	$1,995.91	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$12,895.78	$2,010,288.78
CB4	929227KY1	$766,000.00	$753,377.37	6.5000000000%	6.5000000000%	$4,080.79	$747.25	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$4,828.04	$752,630.12
CB5	929227KZ8	$766,000.00	$753,377.37	6.5000000000%	6.5000000000%	$4,080.79	$747.25	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$4,828.04	$752,630.12
CB6	929227LA2	$1,029,957.00	$1,012,985.22	6.5000000000%	6.5000000000%	$5,487.00	$1,004.74	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$6,491.74	$1,011,980.48
R	929227KX3	$50.00	$0.00	0.0000000000%	0.0000000000%	$0.04	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.04	$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

Series: WAMU.02S1

Distribution Date: 08/25/2003

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

Total Dist

Ending Class Bal

R_SYN

XXXXXXXXX

$0.00

0.0000000000%

$0.00

Total

$634,874,064.00

$146,697,552.73

$773,250.71

$31,611,298.38

$0.00

$32,384,549.09

$115,086,254.35

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003

Class	Orig Face	Beg Bal	Prin Loss	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
IA1	$20,000,000.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IA2	$28,090,000.00	$6,746,044.32	$0.00	$0.00	$6,746,044.32	0.0000000000	$0.00
IA3	$32,828,000.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IA4	$33,000,000.00	$36,370,006.90	$0.00	$0.00	$19,097,395.73	0.5234124597	$17,272,611.17
IA5	$52,000,000.00	$52,000,000.00	$0.00	$0.00	$0.00	1.0000000000	$52,000,000.00
IA6	$65,000,000.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IA7	$65,000,000.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IA8	$60,000,000.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IA9	$60,000,000.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IA10	$39,758,000.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IA11	$4,969,750.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IA12	$35,242,000.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IA13	$35,000,000.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
IIA1	$33,111,000.00	$6,238,735.38	$0.00	$0.00	$395,204.41	0.1764830712	$5,843,530.97
IIIA1	$120,784,000.00	$27,581,793.31	$0.00	$0.00	$4,965,037.80	0.1872495985	$22,616,755.51
IP	$2,806,046.00	$1,230,982.41	$0.00	$0.00	$310,830.62	0.3279175716	$920,151.79
IIP	$188,195.00	$83,726.62	$0.00	$0.00	$15,606.14	0.3619675337	$68,120.48
IIIP	$635,611.00	$374,080.84	$0.00	$0.00	$59,941.93	0.4942313931	$314,138.91
IIIB1	$369,000.00	$345,316.20	$0.00	$0.00	$1,399.31	0.9320240921	$343,916.89
IIIB2	$246,000.00	$230,210.80	$0.00	$0.00	$932.87	0.9320241057	$229,277.93
IIIB3	$493,000.00	$461,357.43	$0.00	$0.00	$1,869.54	0.9320241176	$459,487.89
IIIB4	$369,000.00	$345,316.20	$0.00	$0.00	$1,399.31	0.9320240921	$343,916.89
IIIB5	$184,000.00	$172,190.17	$0.00	$0.00	$697.76	0.9320239674	$171,492.41
IIIB6	$188,205.00	$176,125.51	$0.00	$0.00	$713.70	0.9320252384	$175,411.81
CB1	$7,161,000.00	$7,042,996.43	$0.00	$0.00	$6,985.67	0.9825458400	$7,036,010.76
CB2	$2,813,000.00	$2,766,645.56	$0.00	$0.00	$2,744.13	0.9825458336	$2,763,901.43
CB3	$2,046,000.00	$2,012,284.69	$0.00	$0.00	$1,995.91	0.9825458358	$2,010,288.78
CB4	$766,000.00	$753,377.37	$0.00	$0.00	$747.25	0.9825458486	$752,630.12
CB5	$766,000.00	$753,377.37	$0.00	$0.00	$747.25	0.9825458486	$752,630.12
CB6	$1,029,957.00	$1,012,985.22	$0.00	$0.00	$1,004.74	0.9825463393	$1,011,980.48
R	$50.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003

Class	Orig Face	Beg Bal	Prin Loss	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
R_SYN	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
Total	$634,874,064.00	$146,697,552.73	$0.00	$0.00	$31,611,298.38	0.1812741469	$115,086,254.35

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003
PER $1000 DENOMINATION
Class	Orig Face	Beg Bal	Prin Loss	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
IA1	$20,000,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IA2	$28,090,000.00	240.15821716	0.00000000	0.00000000	240.15821716	0.0000000000	0.00000000
IA3	$32,828,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IA4	$33,000,000.00	1,102.12142121	0.00000000	0.00000000	578.70896152	0.5234124597	523.41245970
IA5	$52,000,000.00	1,000.00000000	0.00000000	0.00000000	0.00000000	1.0000000000	1,000.00000000
IA6	$65,000,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IA7	$65,000,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IA8	$60,000,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IA9	$60,000,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IA10	$39,758,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IA11	$4,969,750.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IA12	$35,242,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IA13	$35,000,000.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
IIA1	$33,111,000.00	188.41881490	0.00000000	0.00000000	11.93574371	0.1764830712	176.48307118
IIIA1	$120,784,000.00	228.35634943	0.00000000	0.00000000	41.10675089	0.1872495985	187.24959854
IP	$2,806,046.00	438.68931942	0.00000000	0.00000000	110.77174786	0.3279175716	327.91757156
IIP	$188,195.00	444.89290364	0.00000000	0.00000000	82.92536996	0.3619675337	361.96753368
IIIP	$635,611.00	588.53739158	0.00000000	0.00000000	94.30599848	0.4942313931	494.23139310
IIIB1	$369,000.00	935.81626016	0.00000000	0.00000000	3.79216802	0.9320240921	932.02409214
IIIB2	$246,000.00	935.81626016	0.00000000	0.00000000	3.79215447	0.9320241057	932.02410569
IIIB3	$493,000.00	935.81628803	0.00000000	0.00000000	3.79217039	0.9320241176	932.02411765
IIIB4	$369,000.00	935.81626016	0.00000000	0.00000000	3.79216802	0.9320240921	932.02409214
IIIB5	$184,000.00	935.81614130	0.00000000	0.00000000	3.79217391	0.9320239674	932.02396739
IIIB6	$188,205.00	935.81737998	0.00000000	0.00000000	3.79214155	0.9320252384	932.02523844
CB1	$7,161,000.00	983.52135596	0.00000000	0.00000000	0.97551599	0.9825458400	982.54583997
CB2	$2,813,000.00	983.52135087	0.00000000	0.00000000	0.97551724	0.9825458336	982.54583363
CB3	$2,046,000.00	983.52135386	0.00000000	0.00000000	0.97551808	0.9825458358	982.54583578
CB4	$766,000.00	983.52137076	0.00000000	0.00000000	0.97552219	0.9825458486	982.54584856
CB5	$766,000.00	983.52137076	0.00000000	0.00000000	0.97552219	0.9825458486	982.54584856
CB6	$1,029,957.00	983.52185577	0.00000000	0.00000000	0.97551645	0.9825463393	982.54633931
R	$50.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003
PER $1000 DENOMINATION
Class	Orig Face	Beg Bal	Prin Loss	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
R_SYN	$0.00	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003

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
IA1	$20,000,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IA2	$28,090,000.00	6.5000000000%	6.5000000000%	$6,746,044.32	$36,541.07	$0.00	$0.00	$0.00	$36,541.07
IA3	$32,828,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IA4	$33,000,000.00	6.5000000000%	6.5000000000%	$36,370,006.90	$197,004.20	$0.00	$0.00	$0.00	$197,004.20
IA5	$52,000,000.00	6.5000000000%	6.5000000000%	$52,000,000.00	$281,666.67	$0.00	$0.00	$0.00	$281,666.67
IA6	$65,000,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IA7	$65,000,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IA8	$60,000,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IA9	$60,000,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IA10	$39,758,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IA11	$4,969,750.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IA12	$35,242,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IA13	$35,000,000.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
IIA1	$33,111,000.00	6.5000000000%	6.5000000000%	$6,238,735.38	$33,793.15	$0.00	$0.00	$0.00	$33,793.15
IIIA1	$120,784,000.00	6.0000000000%	6.0000000000%	$27,581,793.31	$137,908.97	$0.00	$0.00	$0.00	$137,908.97
IP	$2,806,046.00	0.0000000000%	0.0000000000%	$1,230,982.41	$0.00	$0.00	$0.00	$0.00	$0.00
IIP	$188,195.00	0.0000000000%	0.0000000000%	$83,726.62	$0.00	$0.00	$0.00	$0.00	$0.00
IIIP	$635,611.00	0.0000000000%	0.0000000000%	$374,080.84	$0.00	$0.00	$0.00	$0.00	$0.00
IIIB1	$369,000.00	6.0000000000%	6.0000000000%	$345,316.20	$1,726.58	$0.00	$0.00	$0.00	$1,726.58
IIIB2	$246,000.00	6.0000000000%	6.0000000000%	$230,210.80	$1,151.05	$0.00	$0.00	$0.00	$1,151.05
IIIB3	$493,000.00	6.0000000000%	6.0000000000%	$461,357.43	$2,306.79	$0.00	$0.00	$0.00	$2,306.79
IIIB4	$369,000.00	6.0000000000%	6.0000000000%	$345,316.20	$1,726.58	$0.00	$0.00	$0.00	$1,726.58
IIIB5	$184,000.00	6.0000000000%	6.0000000000%	$172,190.17	$860.95	$0.00	$0.00	$0.00	$860.95
IIIB6	$188,205.00	6.0000000000%	6.0000000000%	$176,125.51	$880.63	$0.00	$0.00	$0.00	$880.63
CB1	$7,161,000.00	6.5000000000%	6.5000000000%	$7,042,996.43	$38,149.56	$0.00	$0.00	$0.00	$38,149.56
CB2	$2,813,000.00	6.5000000000%	6.5000000000%	$2,766,645.56	$14,986.00	$0.00	$0.00	$0.00	$14,986.00
CB3	$2,046,000.00	6.5000000000%	6.5000000000%	$2,012,284.69	$10,899.88	$0.00	$0.00	$0.00	$10,899.88
CB4	$766,000.00	6.5000000000%	6.5000000000%	$753,377.37	$4,080.79	$0.00	$0.00	$0.00	$4,080.79
CB5	$766,000.00	6.5000000000%	6.5000000000%	$753,377.37	$4,080.79	$0.00	$0.00	$0.00	$4,080.79
CB6	$1,029,957.00	6.5000000000%	6.5000000000%	$1,012,985.22	$5,487.00	$0.00	$0.00	$0.00	$5,487.00
R	$50.00	0.0000000000%	0.0000000000%	$0.00	$0.04	$0.00	$0.00	$0.00	$0.04

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003

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
R_SYN	$0.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
Total	$634,874,064.00			$146,697,552.73	$773,250.71	$0.00	$0.00	$0.00	$773,250.71

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003
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
IA1	$20,000,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IA2	$28,090,000.00	6.5000000000%	6.5000000000%	240.15821716	1.30085689	0.00000000	0.00000000	0.00000000	1.30085689
IA3	$32,828,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IA4	$33,000,000.00	6.5000000000%	6.5000000000%	1,102.12142121	5.96982424	0.00000000	0.00000000	0.00000000	5.96982424
IA5	$52,000,000.00	6.5000000000%	6.5000000000%	1,000.00000000	5.41666673	0.00000000	0.00000000	0.00000000	5.41666673
IA6	$65,000,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IA7	$65,000,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IA8	$60,000,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IA9	$60,000,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IA10	$39,758,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IA11	$4,969,750.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IA12	$35,242,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IA13	$35,000,000.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IIA1	$33,111,000.00	6.5000000000%	6.5000000000%	188.41881490	1.02060191	0.00000000	0.00000000	0.00000000	1.02060191
IIIA1	$120,784,000.00	6.0000000000%	6.0000000000%	228.35634943	1.14178178	0.00000000	0.00000000	0.00000000	1.14178178
IP	$2,806,046.00	0.0000000000%	0.0000000000%	438.68931942	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IIP	$188,195.00	0.0000000000%	0.0000000000%	444.89290364	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IIIP	$635,611.00	0.0000000000%	0.0000000000%	588.53739158	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
IIIB1	$369,000.00	6.0000000000%	6.0000000000%	935.81626016	4.67907859	0.00000000	0.00000000	0.00000000	4.67907859
IIIB2	$246,000.00	6.0000000000%	6.0000000000%	935.81626016	4.67906504	0.00000000	0.00000000	0.00000000	4.67906504
IIIB3	$493,000.00	6.0000000000%	6.0000000000%	935.81628803	4.67908722	0.00000000	0.00000000	0.00000000	4.67908722
IIIB4	$369,000.00	6.0000000000%	6.0000000000%	935.81626016	4.67907859	0.00000000	0.00000000	0.00000000	4.67907859
IIIB5	$184,000.00	6.0000000000%	6.0000000000%	935.81614130	4.67907609	0.00000000	0.00000000	0.00000000	4.67907609
IIIB6	$188,205.00	6.0000000000%	6.0000000000%	935.81737998	4.67909992	0.00000000	0.00000000	0.00000000	4.67909992
CB1	$7,161,000.00	6.5000000000%	6.5000000000%	983.52135596	5.32740679	0.00000000	0.00000000	0.00000000	5.32740679
CB2	$2,813,000.00	6.5000000000%	6.5000000000%	983.52135087	5.32740846	0.00000000	0.00000000	0.00000000	5.32740846
CB3	$2,046,000.00	6.5000000000%	6.5000000000%	983.52135386	5.32740958	0.00000000	0.00000000	0.00000000	5.32740958
CB4	$766,000.00	6.5000000000%	6.5000000000%	983.52137076	5.32740209	0.00000000	0.00000000	0.00000000	5.32740209
CB5	$766,000.00	6.5000000000%	6.5000000000%	983.52137076	5.32740209	0.00000000	0.00000000	0.00000000	5.32740209
CB6	$1,029,957.00	6.5000000000%	6.5000000000%	983.52185577	5.32740687	0.00000000	0.00000000	0.00000000	5.32740687
R	$50.00	0.0000000000%	0.0000000000%	0.00000000	0.80000000	0.00000000	0.00000000	0.00000000	0.80000000

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003
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
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
08/2003 DISTRIBUTION REPORT
SERIES: WAMU 02S1 WEIGHTED AVERAGE PC RATE: 6.42708%
POOL NUMBER: 1814
ISSUE DATE: 01/25/2002
CERTIFICATE BALANCE AT ISSUE: $477,328,678.67
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	261		$109,727,260.05
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$109,026.14
Unscheduled Principal Collection/Reversals		$31,143.37
Liquidations-in-full	60	$26,027,381.47
Net principal Distributed		$26,167,550.98	-$26,167,550.98

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	201		$83,559,709.07

SCHEDULED INTEREST AT MORTGAGE RATE:		$625,092.48

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
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
08/2003 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$37,404.29

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:		$26,755,239.17

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
08/2003 DISTRIBUTION REPORT
SERIES: WAMU 02S1 WEIGHTED AVERAGE PC RATE: 6.42528%
POOL NUMBER: 1815
ISSUE DATE: 01/25/2002
CERTIFICATE BALANCE AT ISSUE: $34,276,570.31
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	19		$7,283,902.46
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$7,161.72
Unscheduled Principal Collection/Reversals		$1,107.17
Liquidations-in-full	1	$403,486.29
Net principal Distributed		$411,755.18	-$411,755.18

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	18		$6,872,147.28

SCHEDULED INTEREST AT MORTGAGE RATE:		$41,336.25

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
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
08/2003 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$2,335.30

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:		$450,756.13

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
08/2003 DISTRIBUTION REPORT
SERIES: WAMU 02S1 WEIGHTED AVERAGE PC RATE: 5.92439%
POOL NUMBER: 1816
ISSUE DATE: 01/25/2002
CERTIFICATE BALANCE AT ISSUE: $123,268,816.58
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	65		$29,686,390.86
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$120,343.62
Unscheduled Principal Collection/Reversals		$8,297.62
Liquidations-in-full	12	$4,903,350.98
Net principal Distributed		$5,031,992.22	-$5,031,992.22

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	53		$24,654,398.64

SCHEDULED INTEREST AT MORTGAGE RATE:		$157,807.86

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
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
08/2003 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$11,246.29

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:		$5,178,553.79

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
08/2003 DISTRIBUTION REPORT
SERIES: WAMU 02S1 WEIGHTED AVERAGE PC RATE: 6.32526%
POOL NUMBER: ALL
ISSUE DATE: 01/25/2002
CERTIFICATE BALANCE AT ISSUE: $634,874,065.56
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	345		$146,697,553.37
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		$236,531.48
Unscheduled Principal Collection/Reversals		$40,548.16
Liquidations-in-full	73	$31,334,218.74
Net principal Distributed		$31,611,298.38	-$31,611,298.38

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	272		$115,086,254.99

SCHEDULED INTEREST AT MORTGAGE RATE:		$824,236.59

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
Net Other Distributions		$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
08/2003 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$50,985.88

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:		$32,384,549.09

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003

Distribution by Group
Pool ID		Principal		Interest		Total
Pool - 1814		$26,167,550.98		$587,688.19		$26,755,239.17
Pool - 1815		$411,755.18		$39,000.95		$450,756.13
Pool - 1816		$5,031,992.22		$146,561.57		$5,178,553.79
Aggregate		$31,611,298.38		$773,250.71		$32,384,549.09

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 - 1814	$109,727,260.05	261	60	201	$83,559,709.07	$109,026.14	$26,027,381.47	$31,143.37	$26,167,550.98
Pool - 1815	$7,283,902.46	19	1	18	$6,872,147.28	$7,161.72	$403,486.29	$1,107.17	$411,755.18
Pool - 1816	$29,686,390.86	65	12	53	$24,654,398.64	$120,343.62	$4,903,350.98	$8,297.62	$5,031,992.22
Aggregate	$146,697,553.37	345	73	272	$115,086,254.99	$236,531.48	$31,334,218.74	$40,548.16	$31,611,298.38

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 - 1814	1	$820,358.39	1	$499,966.02	0	$0.00	0	$0.00
Pool - 1815	0	$0.00	0	$0.00	0	$0.00	0	$0.00
Pool - 1816	1	$489,605.09	0	$0.00	0	$0.00	0	$0.00
Aggregate	2	$1,309,963.48	1	$499,966.02	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 - 1814		0		$0.00		0		$0.00
Pool - 1815		0		$0.00		0		$0.00
Pool - 1816		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(1814)			0			$0.00
Group 2(1815)			0			$0.00
Group 3(1816)			0			$0.00
Aggregate			0			$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003

INSURANCE RESERVES - Group 1(1814)
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	$0.00	$0.00	$0.00	$0.00	$0.00
Bankruptcy Bond
Single-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$0.00	$0.00	$0.00	$0.00	$0.00

INSURANCE RESERVES - Group 2(1815)
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	$0.00	$0.00	$0.00	$0.00	$0.00
Bankruptcy Bond
Single-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$0.00	$0.00	$0.00	$0.00	$0.00

INSURANCE RESERVES - Group 3(1816)
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	$0.00	$0.00	$0.00	$0.00	$0.00
Bankruptcy Bond
Single-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$0.00	$0.00	$0.00	$0.00	$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003

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	$0.00	$0.00	$0.00	$0.00	$0.00
Bankruptcy Bond
Single-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Multi-Units	$0.00	$0.00	$0.00	$0.00	$0.00
Mortgage Repurchase	$0.00	$0.00	$0.00	$0.00	$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.02S1
Distribution Date: 08/25/2003

The Class Principal Balances of each Class of the Class CB1,CB2,CB3,CB4,CB5,CB6 Certificatesimmediately after the principal and interest distribution on 200308 are as follows:

Class			Class Principal Balance
CB1			$7,036,010.76
CB2			$2,763,901.43
CB3			$2,010,288.78
CB4			$752,630.12
CB5			$752,630.12
CB6			$1,011,980.48
Total			$14,327,441.70
Capitalized items used but not defined herein have the meanings ascribed to them in the Prospectus Supplement.

The Class Principal Balances of each Class of the Class CB1,CB2,CB3,CB4,CB5,CB6 Certificatesimmediately after the principal and interest distribution on 200308 are as follows:

Class			Class Principal Balance
CB1			$7,036,010.76
CB2			$2,763,901.43
CB3			$2,010,288.78
CB4			$752,630.12
CB5			$752,630.12
CB6			$1,011,980.48
Total			$14,327,441.70
Capitalized items used but not defined herein have the meanings ascribed to them in the Prospectus Supplement.

The Class Principal Balances of each Class of the Class IIIB1,IIIB2,IIIB3,IIIB4,IIIB5,IIIB6 Certificatesimmediately after the principal and interest distribution on 200308 are as follows:

Class			Class Principal Balance
IIIB1			$343,916.89
IIIB2			$229,277.93
IIIB3			$459,487.89
IIIB4			$343,916.89
IIIB5			$171,492.41
IIIB6			$175,411.81
Total			$1,723,503.82
Capitalized items used but not defined herein have the meanings ascribed to them in the Prospectus Supplement.

WAMU MORTGAGE PASS THROUGH CERTIFICATES 2002-S1 8-K