Exhibit 99.1350CERT


   Certification Pursuant to Section 906 of the Sarbanes Oxley Act


I, Robert C. Doll, Jr., Chief Executive Officer of CMA Tax-Exempt
Fund and Master Tax-Exempt Trust (together, 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 23, 2005


                                     /s/ Robert C. Doll, Jr.
                                     -----------------------
                                     Robert C. Doll, Jr.,
                                     Chief Executive Officer of
                                     CMA Tax-Exempt Fund and
                                     Master Tax-Exempt Trust


A signed original of this written statement required by Section 906,
or other document authenticating, acknowledging, or otherwise
adopting the signature that appears in typed form within the
electronic version of this written statement required by Section
906, has been provided to CMA Tax-Exempt Fund and Master Tax-Exempt
Trust and will be retained by CMA Tax-Exempt Fund and Master Tax-
Exempt Trust and furnished to the Securities and Exchange Commission
or its staff upon request.



Exhibit 99.1350CERT


   Certification Pursuant to Section 906 of the Sarbanes Oxley Act


I, Donald C. Burke, Chief Financial Officer of CMA Tax-Exempt Fund
and Master Tax-Exempt Trust (together, 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 23, 2005


                                     /s/ Donald C. Burke
                                     -------------------
                                     Donald C. Burke,
                                     Chief Financial Officer of
                                     CMA Tax-Exempt Fund and
                                     Master Tax-Exempt Trust


A signed original of this written statement required by Section 906,
or other document authenticating, acknowledging, or otherwise
adopting the signature that appears in typed form within the
electronic version of this written statement required by Section
906, has been provided to CMA Tax-Exempt Fund and Master Tax-Exempt
Trust and will be retained by CMA Tax-Exempt Fund and Master Tax-
Exempt Trust and furnished to the Securities and Exchange Commission
or its staff upon request.