Exhibit 99.1350CERT

         Certification Pursuant to Section 906 of the Sarbanes Oxley Act

I, Terry K. Glenn, President of CMA Massachusetts Municipal Money Fund (the
"Fund"), certify that:

      1.    The N-CSR of the Fund (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 Fund.

Dated: May 21, 2003

                                          /s/ Terry K. Glenn
                                          --------------------------------------
                                          Terry K. Glenn,
                                          President of
                                          CMA Massachusetts Municipal Money Fund


Exhibit 99.1350CERT

         Certification Pursuant to Section 906 of the Sarbanes Oxley Act

I, Donald C. Burke, Chief Financial Officer of CMA Massachusetts Municipal Money
Fund (the "Fund"), certify that:

      1.    The N-CSR of the Fund (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 Fund.

Dated: May 21, 2003

                                          /s/ Donald C. Burke
                                          --------------------------------------
                                          Donald C. Burke,
                                          Chief Financial Officer of
                                          CMA Massachusetts Municipal Money Fund