Exhibit (a)(3) EX-99-906CERT Certification pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 Donald A. Gignac, Chief Executive Officer and Karen D. Gillogly, Chief Financial Officer of the State Street Master Funds (the "Trust"), certify that: 1. This Form N-CSR filing for the Trust (the "Report") fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and 2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Trust. By: /s/ Donald A. Gignac ------------------------------------------- Donald A. Gignac Chief Executive Officer of the Trust Date: April 29, 2004 By: /s/ Karen D. Gillogly ------------------------------------------- Karen D. Gillogly Chief Financial Officer of the Trust Date: April 29, 2004