2008-10-10 21:37:00 -

- Fitch Ratings has affirmed all classes of residential mortgage-backed securities (RMBS) from the Washington Mutual (WaMu) Mortgage Securities Corp. prime RMBS transaction listed below:

Series 2002-MS1 TOTAL

--Class I-A4 at 'AAA';

--Class I-A13 at 'AAA';

--Class I-A22 at 'AAA';

--Class II-A1 at 'AAA';

--Class II-A4 at 'AAA';

--Class III-A4 at 'AAA';

--Class III-A11 at 'AAA';

--Class CX at 'AAA';

--Class CP at 'AAA';

--Class CB-1 at 'AAA';

--Class CB-2 at 'AAA';

--Class CB-3 at 'AAA';

--Class CB-4 at 'AAA';

--Class CB-5 at 'AA'.

The rating actions were taken as part as Fitch's ongoing surveillance process of existing transactions.

Further information regarding current delinquency, loss, and credit enhancement statistics is also available at www.fitchratings.com.

Fitch's rating definitions and the terms of use of such ratings are available on the agency's public site, www.fitchratings.com. Published ratings, criteria and methodologies are available from this site, at all times. Fitch's code of conduct, confidentiality, conflicts of interest, affiliate firewall, compliance and other relevant policies and procedures are also available from the 'Code of Conduct' section of this site.

Fitch Ratings, New York
Tara Sweeney, 212-908-0347
Michele Patterson, 212-908-0779
Sandro Scenga, 212-908-0278 (Media Relations)