Exhibit 99.1350CERT


        Certification Pursuant to Section 906 of the Sarbanes Oxley Act


I, Robert C. Doll, Jr., Chief Executive Officer of Muni Intermediate Duration
Fund, Inc. (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: July 21, 2006


                                         /s/ Robert C. Doll, Jr.
                                         -----------------------
                                         Robert C. Doll, Jr.,
                                         Chief Executive Officer of
                                         Muni Intermediate Duration Fund, Inc.


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 Muni Intermediate
Duration Fund, Inc. and will be retained by Muni Intermediate Duration Fund,
Inc. 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 Muni Intermediate Duration Fund,
Inc. (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: July 21, 2006


                                         /s/ Donald C. Burke
                                         -------------------
                                         Donald C. Burke,
                                         Chief Financial Officer of
                                         Muni Intermediate Duration Fund, Inc.


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 Muni Intermediate
Duration Fund, Inc. and will be retained by Muni Intermediate Duration Fund,
Inc. and furnished to the Securities and Exchange Commission or its staff upon
request.