EX-99.906CERT

Section 906 Certifications


                CERTIFICATION PURSUANT TO 18 U.S.C SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


John V. Murphy, Principal Executive Officer, and Brian W. Wixted, Principal
Financial Officer, of Oppenheimer Institutional Money Market Fund (the
"Registrant"), each certify to the best of his knowledge that:

1.   The Registrant's periodic report on Form N-CSR for the period ended
     11/30/2007 (the "Form N-CSR") fully complies with the requirements of
     Section 15(d) of the Securities Exchange Act of 1934, as amended; and

2.   The information contained in the Form N-CSR fairly presents, in all
     material respects, the financial condition and results of operations of the
     Registrant. This certification is being furnished to the Commission solely
     pursuant to 18 U.S.C. ss. 1350 and is not being filed as part of the Form
     N-CSR filed with the Commission.


Principal Executive Officer                          Principal Financial Officer


Oppenheimer Institutional Money                      Oppenheimer Institutional
Market Fund                                          Money Market Fund



/s/ John V. Murphy                                   /s/ Brian W. Wixted
- -------------------------------                      ---------------------------
John V. Murphy                                       Brian W. Wixted
Date:  01/14/2008                                    Date:  01/14/2008