Certification Filed as Exhibit 12(b) to Form N-CSR

CERTIFICATION

I, Mark R. Fetting, Chief Executive Officer of Legg Mason Cash Reserve Trust (the “Trust”), certify that, to my knowledge:

1. The Trust’s periodic report on Form N-CSR for the period ended August 31, 2005 fully complies with the requirements of Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. Section 78m(a) or 78o(d)); and

2. The information contained in such Form N-CSR fairly presents, in all material aspects, the financial condition and results of operations of the Trust.

/s/ Mark R. Fetting   Mark R. Fetting
President October 26, 2005   Date

Certification Filed as Exhibit 12(b) to Form N-CSR

CERTIFICATION

I, Marie K. Karpinski, Chief Financial Officer of Legg Mason Cash Reserve Trust (the “Trust”), certify that, to my knowledge:

1. The Trust’s periodic report on Form N-CSR for the period ended August 31, 2005 fully complies with the requirements of Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. Section 78m(a) or 78o(d)); and

2. The information contained in such Form N-CSR fairly presents, in all material aspects, the financial condition and results of operations of the Trust.

/s/ Marie K. Karpinski   Marie K. Karpinski
Vice President and Treasurer October 25, 2005   Date