May 12, 2006





Nancy Vann
Vice President and Assistant Counsel
OppenheimerFunds, Inc.
2 World Financial Center
225 Liberty Street, 16th Floor
New York, New York 10281-1008

      Re:	Oppenheimer Institutional Money Market Fund
		File Numbers 333-133173; 811-21888

Dear Ms. Vann:

      We have reviewed the registration statement on Form N-1A for
the Oppenheimer Institutional Money Market Fund ("Fund") filed
with
the Commission on April 10, 2006.  Based upon Securities Act
Release
No. 6510 and the representations contained in the cover letter
which
accompanied the filing, we conducted a selective review of the
registration statement. We have the following comments.

Prospectus

The Fund`s Principal Investment Policies and Risks

	Please disclose that the Fund will only invest in dollar-
denominated securities.  Also, please confirm to the staff that
the
Fund will not invest in inverse floaters.

Fees and Expenses

		Please remove the paragraph discussing other expenses
from
between the fee table and Example and insert it immediately after
the
Example.

	Example

		Please delete the word "estimated" from the second
sentence
of the paragraph immediately preceding the table.



At What Price Are Shares Sold?

	Please disclose how an investor may know whether an agent has
been appointed by the Distributor to receive a purchase order.

      Please define the term "in good order" when it is first used
in
this section.

      Please include the applicable time zone in all references to
deadlines.

      The paragraph titled "Buying through a Dealer" is unclear in
that it does not explain the "alternative arrangements with the
Distributor."  Also, to the extent the paragraph suggests that
orders
placed with a dealer prior to 5:00 pm may not receive that day`s
offering price, it appears to be contrary to Rule 22c-1 under the
Investment Company Act of 1940 ("1940 Act").  Please clarify.

How to Sell Shares

	Why must redemption orders be received only by the Transfer
Agent, rather than the Fund or its other agents, e.g., brokers or
financial institutions?   Also, please delete the words "and is
accepted" from the second sentence of the first paragraph of this
section.

How Do You Sell Shares by Mail?

	Please disclose when mail redemptions are effected.

Can You Sell Shares Through Your Dealer?

	Please clarify what is meant by the assertion that brokers or
dealers may charge shareholders for selling shares.  Is this an
additional sales load?  How does this arrangement comply with the
requirements of Rules 22c-1 and 22d-1 under the 1940 Act?

How Can You Buy Class P Shares?

      In the event the Distributor incurs costs greater than the
0.25% of the average annual net assets of Class P shares of the
Fund,
may the Fund carry forward the unreimbursed expenses and make
payment
to the Distributor in future years?  If so, please disclose here.

Back Cover

	Please set forth the 1940 Act file number for the Fund.



Statement of Additional Information

Investment Restrictions

      Please include in the Fund`s diversification policy the
provision that the Fund can not invest in more than 10 percent of
the
outstanding voting securities of an issuer.

      Please exclude from the exception to the Fund`s
concentration
policy foreign branches of U. S. banks, unless it can be
demonstrated
that the banks are regulated in a manner similar to domestic
banks.

      Please disclose that the Fund may not concentrate in any one
industry or group of industries.

      Please disclose the percentage limitations on the Fund`s
ability to borrow, make loans, and invest in real estate and
physical
commodities.

Closing

      We note that portions of the filing are incomplete. We may
have
additional comments on such portions when you complete them in a
pre-
effective amendment, on disclosures made in response to this
letter,
on information supplied supplementally, or on exhibits added in
any
pre-effective amendments.  Please note that comments we give in
one
section apply to other sections in the filing that contain the
same
or similar disclosure.
      Please advise us if you have submitted or expect to submit
an
exemptive application or no-action request in connection with your
registration statement.
      Response to this letter should be in the form of a pre-
effective amendment filed pursuant to Rule 472 under the
Securities
Act. Where no change will be made in the filing in response to a
comment, please indicate this fact in a supplemental letter and
briefly state the basis for your position.
      We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filings reviewed by the staff to
be
certain that they have provided all information investors require
for
an informed decision. Since the Fund and its management are in
possession of all facts relating to the Fund`s disclosure, they
are
responsible for the accuracy and adequacy of the disclosures they
have made.
	Notwithstanding our comments, in the event the Fund requests
acceleration of the effective date of the pending registration
statement, it should furnish a letter, at the time of such
request,
acknowledging that
* should the Commission or the staff, acting pursuant to delegated
authority, declare the filing effective, it does not foreclose the
Commission from taking any action with respect to the filing;
* the action of the Commission or the staff, acting pursuant to
delegated authority, in declaring the filing effective, does not
relieve the Fund from its full responsibility for the adequacy and
accuracy of the disclosure in the filing; and
* the Fund may not assert this action as defense in any proceeding
initiated by the Commission or any person under the federal
securities laws of the United States.
      In addition, please be advised that the Division of
Enforcement
has access to all information you provide to the staff of the
Division of Investment Management in connection with our review of
your filing or in response to our comments on your filing.
      Should you have any questions regarding this letter, please
contact me at (202) 551-6965.



						Sincerely,



						Vincent J. Di Stefano
						Senior Counsel

Ms. Nancy Vann, Esq.
OppenheimerFunds, Inc.
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