WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.05AR1
Distribution Date: 04/25/2005

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
A1A	939336X40	$716,000,000.00	$708,437,683.09	3.1950000000%	3.1950000000%	$1,949,089.18	$4,089,533.29	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$6,038,622.47	$704,348,149.80
A1B	939336X57	$477,350,000.00	$472,308,279.36	3.2650000000%	3.2650000000%	$1,327,907.85	$2,726,450.72	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$4,054,358.57	$469,581,828.64
A2A1	939336X65	$764,000,000.00	$755,930,712.13	3.2150000000%	3.2150000000%	$2,092,773.18	$4,363,691.95	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$6,456,465.12	$751,567,020.18
A2A2	939336X73	$352,300,000.00	$346,905,205.77	3.1250000000%	3.1250000000%	$933,512.27	$2,917,385.09	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$3,850,897.36	$343,987,820.68
A2A3	939336X81	$158,479,000.00	$158,479,000.00	3.2750000000%	3.2750000000%	$446,932.79	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$446,932.79	$158,479,000.00
A2B	939336X99	$225,000,000.00	$222,623,573.59	3.2750000000%	3.2750000000%	$627,829.40	$1,285,118.70	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$1,912,948.10	$221,338,454.89
A3	939336Z22	$100,000,000.00	$98,943,810.49	3.2350000000%	3.2350000000%	$275,627.22	$571,163.87	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$846,791.09	$98,372,646.62
X	939336Y56	$0.00	$0.00	0.0000000000%	0.0000000000%	$1,532,488.38	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$1,532,488.38	$0.00
X_NOTIONAL	XXXXXXXXX	$2,971,414,173.32	$2,941,908,771.19	0.6250996212%	0.6250996212%	$1,532,488.38	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$1,532,488.38	$2,925,953,679.13
X_PRINCIPAL	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
B1	939336Y23	$65,371,000.00	$65,369,325.59	3.4250000000%	3.4250000000%	$186,574.95	$641.09	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$187,216.05	$65,368,684.50
B2	939336Y31	$40,114,000.00	$40,112,972.52	3.8250000000%	3.8250000000%	$127,860.10	$393.40	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$128,253.50	$40,112,579.12
B3	939336Y49	$22,285,000.00	$22,284,429.20	3.9736058030%	3.9736058030%	$73,791.28	$218.55	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$74,009.83	$22,284,210.65
B4	939336Y72	$20,799,000.00	$20,798,467.25	3.9736058030%	3.9736058030%	$68,870.76	$203.98	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$69,074.73	$20,798,263.27
B5	939336Y80	$17,828,000.00	$17,827,543.35	3.9736058030%	3.9736058030%	$59,033.02	$174.84	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$59,207.86	$17,827,368.51
B6	939336Y98	$11,888,073.32	$11,887,768.83	3.9736058030%	3.9736058030%	$39,364.42	$116.64	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.05	$0.00	$39,481.06	$11,887,652.24
Y	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
R	939336Y64	$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
YIELD_PAYMENTS	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
TFEE	XXXXXXXXX	$0.00	$0.00	0.0000000000%	0.0000000000%	$637.41	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$637.41	$0.00
Total		$2,971,414,173.32	$2,941,908,771.17			$9,741,654.89	$15,955,092.11	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.05	$0.00	$25,696,747.00	$2,925,953,679.11

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.05AR1
Distribution Date: 04/25/2005

Class	Orig Face	Beg Bal	Prin Loss	Prin Reimbursed	Subsequent Recoveries	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
A1A	$716,000,000.00	$708,437,683.09	$0.00	$0.00	$0.00	$0.00	$4,089,533.29	0.9837264662	$704,348,149.80
A1B	$477,350,000.00	$472,308,279.36	$0.00	$0.00	$0.00	$0.00	$2,726,450.72	0.9837264662	$469,581,828.64
A2A1	$764,000,000.00	$755,930,712.13	$0.00	$0.00	$0.00	$0.00	$4,363,691.95	0.9837264662	$751,567,020.18
A2A2	$352,300,000.00	$346,905,205.77	$0.00	$0.00	$0.00	$0.00	$2,917,385.09	0.9764059628	$343,987,820.68
A2A3	$158,479,000.00	$158,479,000.00	$0.00	$0.00	$0.00	$0.00	$0.00	1.0000000000	$158,479,000.00
A2B	$225,000,000.00	$222,623,573.59	$0.00	$0.00	$0.00	$0.00	$1,285,118.70	0.9837264662	$221,338,454.89
A3	$100,000,000.00	$98,943,810.49	$0.00	$0.00	$0.00	$0.00	$571,163.87	0.9837264662	$98,372,646.62
X	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
X_NOTIONAL	$2,971,414,173.32	$2,941,908,771.19	$0.00	$0.00	$0.00	$0.00	$0.00	0.9847007211	$2,925,953,679.13
X_PRINCIPAL	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
B1	$65,371,000.00	$65,369,325.59	$0.00	$0.00	$0.00	$0.00	$641.09	0.9999645791	$65,368,684.50
B2	$40,114,000.00	$40,112,972.52	$0.00	$0.00	$0.00	$0.00	$393.40	0.9999645789	$40,112,579.12
B3	$22,285,000.00	$22,284,429.20	$0.00	$0.00	$0.00	$0.00	$218.55	0.9999645793	$22,284,210.65
B4	$20,799,000.00	$20,798,467.25	$0.00	$0.00	$0.00	$0.00	$203.98	0.9999645786	$20,798,263.27
B5	$17,828,000.00	$17,827,543.35	$0.00	$0.00	$0.00	$0.00	$174.84	0.9999645788	$17,827,368.51
B6	$11,888,073.32	$11,887,768.83	$0.00	$0.05	$0.00	$0.00	$116.64	0.9999645796	$11,887,652.24
Y	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
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
YIELD_PAYMENTS	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
TFEE	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	0.0000000000	$0.00
Total	$2,971,414,173.32	$2,941,908,771.17	$0.00	$0.05	$0.00	$0.00	$15,955,092.11	0.9847007211	$2,925,953,679.11

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.05AR1
Distribution Date: 04/25/2005
PER $1000 DENOMINATION
Class	Orig Face	Beg Bal	Prin Loss	Prin Reimbursed	Subsequent Recoveries	Deferred Interest	Total Prin	End Cert Pct	End Cert Bal
A1A	$716,000,000.00	989.43810487	0.00000000	0.00000000	0.00000000	0.00000000	5.71163867	0.9837264662	983.72646620
A1B	$477,350,000.00	989.43810487	0.00000000	0.00000000	0.00000000	0.00000000	5.71163867	0.9837264662	983.72646620
A2A1	$764,000,000.00	989.43810488	0.00000000	0.00000000	0.00000000	0.00000000	5.71163868	0.9837264662	983.72646620
A2A2	$352,300,000.00	984.68693094	0.00000000	0.00000000	0.00000000	0.00000000	8.28096818	0.9764059628	976.40596276
A2A3	$158,479,000.00	1,000.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	1.0000000000	1,000.00000000
A2B	$225,000,000.00	989.43810484	0.00000000	0.00000000	0.00000000	0.00000000	5.71163867	0.9837264662	983.72646618
A3	$100,000,000.00	989.43810490	0.00000000	0.00000000	0.00000000	0.00000000	5.71163870	0.9837264662	983.72646620
X	$0.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
X_NOTIONAL	$2,971,414,173.32	990.07024925	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.9847007211	984.70072109
X_PRINCIPAL	$0.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
B1	$65,371,000.00	999.97438604	0.00000000	0.00000000	0.00000000	0.00000000	0.00980695	0.9999645791	999.96457909
B2	$40,114,000.00	999.97438600	0.00000000	0.00000000	0.00000000	0.00000000	0.00980705	0.9999645789	999.96457895
B3	$22,285,000.00	999.97438636	0.00000000	0.00000000	0.00000000	0.00000000	0.00980705	0.9999645793	999.96457931
B4	$20,799,000.00	999.97438579	0.00000000	0.00000000	0.00000000	0.00000000	0.00980720	0.9999645786	999.96457859
B5	$17,828,000.00	999.97438580	0.00000000	0.00000000	0.00000000	0.00000000	0.00980705	0.9999645788	999.96457875
B6	$11,888,073.32	999.97438693	0.00000000	0.00000421	0.00000000	0.00000000	0.00981151	0.9999645796	999.96457963
Y	$0.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
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
YIELD_PAYMENTS	$0.00	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.0000000000	0.00000000
TFEE	$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.05AR1
Distribution Date: 04/25/2005

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
A1A	$716,000,000.00	3.1950000000%	3.1950000000%	$708,437,683.09	$1,949,089.18	$0.00	$0.00	$0.00	$0.00	$0.00	$1,949,089.18
A1B	$477,350,000.00	3.2650000000%	3.2650000000%	$472,308,279.36	$1,327,907.85	$0.00	$0.00	$0.00	$0.00	$0.00	$1,327,907.85
A2A1	$764,000,000.00	3.2150000000%	3.2150000000%	$755,930,712.13	$2,092,773.18	$0.00	$0.00	$0.00	$0.00	$0.00	$2,092,773.18
A2A2	$352,300,000.00	3.1250000000%	3.1250000000%	$346,905,205.77	$933,512.27	$0.00	$0.00	$0.00	$0.00	$0.00	$933,512.27
A2A3	$158,479,000.00	3.2750000000%	3.2750000000%	$158,479,000.00	$446,932.79	$0.00	$0.00	$0.00	$0.00	$0.00	$446,932.79
A2B	$225,000,000.00	3.2750000000%	3.2750000000%	$222,623,573.59	$627,829.40	$0.00	$0.00	$0.00	$0.00	$0.00	$627,829.40
A3	$100,000,000.00	3.2350000000%	3.2350000000%	$98,943,810.49	$275,627.22	$0.00	$0.00	$0.00	$0.00	$0.00	$275,627.22
X	$0.00	0.0000000000%	0.0000000000%	$0.00	$1,532,488.38	$0.00	$0.00	$0.00	$0.00	$0.00	$1,532,488.38
X_NOTIONAL	$2,971,414,173.32	0.6250996212%	0.6250996212%	$2,941,908,771.19	$1,532,488.38	$0.00	$0.00	$0.00	$0.00	$0.00	$1,532,488.38
X_PRINCIPAL	$0.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
B1	$65,371,000.00	3.4250000000%	3.4250000000%	$65,369,325.59	$186,574.95	$0.00	$0.00	$0.00	$0.00	$0.00	$186,574.95
B2	$40,114,000.00	3.8250000000%	3.8250000000%	$40,112,972.52	$127,860.10	$0.00	$0.00	$0.00	$0.00	$0.00	$127,860.10
B3	$22,285,000.00	3.9736058030%	3.9736058030%	$22,284,429.20	$73,791.28	$0.00	$0.00	$0.00	$0.00	$0.00	$73,791.28
B4	$20,799,000.00	3.9736058030%	3.9736058030%	$20,798,467.25	$68,870.76	$0.00	$0.00	$0.00	$0.00	$0.00	$68,870.76
B5	$17,828,000.00	3.9736058030%	3.9736058030%	$17,827,543.35	$59,033.02	$0.00	$0.00	$0.00	$0.00	$0.00	$59,033.02
B6	$11,888,073.32	3.9736058030%	3.9736058030%	$11,887,768.83	$39,364.42	$0.00	$0.00	$0.00	$0.00	$0.00	$39,364.42
Y	$0.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
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
YIELD_PAYMENTS	$0.00	0.0000000000%	0.0000000000%	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00	$0.00
TFEE	$0.00	0.0000000000%	0.0000000000%	$0.00	$637.41	$0.00	$0.00	$0.00	$0.00	$0.00	$637.41
Total	$2,971,414,173.32			$2,941,908,771.17	$9,741,654.89	$0.00	$0.00	$0.00	$0.00	$0.00	$9,741,654.89

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.05AR1
Distribution Date: 04/25/2005
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
A1A	$716,000,000.00	3.1950000000%	3.1950000000%	989.43810487	2.72219159	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.72219159
A1B	$477,350,000.00	3.2650000000%	3.2650000000%	989.43810487	2.78183272	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.78183272
A2A1	$764,000,000.00	3.2150000000%	3.2150000000%	989.43810488	2.73923191	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.73923191
A2A2	$352,300,000.00	3.1250000000%	3.1250000000%	984.68693094	2.64976517	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.64976517
A2A3	$158,479,000.00	3.2750000000%	3.2750000000%	1,000.00000000	2.82013888	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.82013888
A2B	$225,000,000.00	3.2750000000%	3.2750000000%	989.43810484	2.79035289	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.79035289
A3	$100,000,000.00	3.2350000000%	3.2350000000%	989.43810490	2.75627220	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.75627220
X	$0.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
X_NOTIONAL	$2,971,414,173.32	0.6250996212%	0.6250996212%	990.07024925	0.51574378	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.51574378
X_PRINCIPAL	$0.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
B1	$65,371,000.00	3.4250000000%	3.4250000000%	999.97438604	2.85409356	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	2.85409356
B2	$40,114,000.00	3.8250000000%	3.8250000000%	999.97438600	3.18741836	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.18741836
B3	$22,285,000.00	3.9736058030%	3.9736058030%	999.97438636	3.31125331	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.31125331
B4	$20,799,000.00	3.9736058030%	3.9736058030%	999.97438579	3.31125343	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.31125343
B5	$17,828,000.00	3.9736058030%	3.9736058030%	999.97438580	3.31125309	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.31125309
B6	$11,888,073.32	3.9736058030%	3.9736058030%	999.97438693	3.31125313	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	3.31125313
Y	$0.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
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
YIELD_PAYMENTS	$0.00	0.0000000000%	0.0000000000%	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000	0.00000000
TFEE	$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
04/2005 DISTRIBUTION REPORT
SERIES: WAMU 05AR1
WEIGHTED AVERAGE PC RATE: 3.97361%
WEIGHTED AVERAGE MATURITY: 363.34417
WEIGHTED AVERAGE LOAN AGE: 5.14656
POOL NUMBER: 2652
ISSUE DATE: 01/18/2005
CERTIFICATE BALANCE AT ISSUE: $2,971,414,173.32
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	5433		$2,941,908,771.19
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		($1,227,311.42)
Unscheduled Principal Collection/Reversals		$2,504,088.47
Liquidations-in-full	28	$14,678,315.01
Subsequent Recoveries		$0.00
Net principal Distributed		$15,955,092.06	-$15,955,092.06

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	5405		$2,925,953,679.13

SCHEDULED INTEREST AT MORTGAGE RATE:		$10,783,580.85

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
04/2005 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$1,041,925.91

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:		$25,696,747.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
04/2005 DISTRIBUTION REPORT
SERIES: WAMU 05AR1
WEIGHTED AVERAGE PC RATE: 3.97361%
WEIGHTED AVERAGE MATURITY: 363.34417
WEIGHTED AVERAGE LOAN AGE: 5.14656
POOL NUMBER: ALL
ISSUE DATE: 01/18/2005
CERTIFICATE BALANCE AT ISSUE: $2,971,414,173.32
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END:	5433		$2,941,908,771.19
PRINCIPAL POOL COLLECTION(S):
Scheduled Principal Collection Due Current Month		($1,227,311.42)
Unscheduled Principal Collection/Reversals		$2,504,088.47
Liquidations-in-full	28	$14,678,315.01
Subsequent Recoveries		$0.00
Net principal Distributed		$15,955,092.06	-$15,955,092.06

CAPITAL LOSS (PRINCIPAL WRITTEN OFF):			$0.00

BALANCE CURRENT FISCAL MONTH-END:	5405		$2,925,953,679.13

SCHEDULED INTEREST AT MORTGAGE RATE:		$10,783,580.85

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
04/2005 DISTRIBUTION REPORT
	TOTAL NUMBER OF MORTAGES	CERTIFICATE ACCOUNT ACTIVITY (@ PCRATE)	CERTIFICATE BALANCE OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:		$1,041,925.91

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:		$25,696,747.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.05AR1
Distribution Date: 04/25/2005

Distribution by Group
Pool ID		Principal		Interest		Total
Pool - 2652		$15,955,092.06		$9,741,654.94		$25,696,747.00
Aggregate		$15,955,092.06		$9,741,654.94		$25,696,747.00

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 - 2652	$2,941,908,771.19	5433	28	5405	$2,925,953,679.13	($1,227,311.42)	$14,678,315.01	$2,504,088.47	$15,955,092.06
Aggregate	$2,941,908,771.19	5433	28	5405	$2,925,953,679.13	($1,227,311.42)	$14,678,315.01	$2,504,088.47	$15,955,092.06

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 - 2652	17	$10,892,691.24	2	$1,078,133.06	0	$0.00	0	$0.00
Aggregate	17	$10,892,691.24	2	$1,078,133.06	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 - 2652		0		$0.00		0		$0.00
Aggregate		0		$0.00		0		$0.00

Aggregate Loss Amounts by Group
Pool ID			Count			Loss Amount
Pool - 2652			0			$0.00
Aggregate			0			$0.00

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.05AR1
Distribution Date: 04/25/2005

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	$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 - 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.05AR1
Distribution Date: 04/25/2005

The Subordinate Certificates provide, to the limited extent described in the Prospectus Supplement, credit support, as well as special hazard, bankruptcy, and fraud coverage to certain Certificates. The "Prospectus Supplement" is that certain Prospectus Supplement, dated January 13,2005 to that certain Prospectus Supplement,dated February 10,2004, to which certain certificates were offered. The special hazard, bankruptcy, and Fraud coverage (collectively, "Credit Enhancements") provided by the Subordinate certificates provide coverage to the Loans, subject to the conditions and limitations to payment specified thereunder.



The Class Principal Balances of each Class of the Class B1,B2,B3,B4,B5,B6 Certificatesimmediately after the principal and interest distribution on 200504 are as follows:

Class			Class Principal Balance
B1			$65,368,684.50
B2			$40,112,579.12
B3			$22,284,210.65
B4			$20,798,263.27
B5			$17,827,368.51
B6			$11,887,652.24
Total			$178,278,758.29
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 $0.00, $0.00, $0.00 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."

WaMu Mortgage Pass-Through Certificates, Series 2005-AR1 8-K