CENTENNIAL MONEY MARKET TRUST
                      CENTENNIAL GOVERNMENT TRUST
                      CENTENNIAL TAX EXEMPT TRUST
                  Supplement dated May 20, 1998 to the
                   Prospectuses dated October 1, 1997

This Supplement to the  Prospectuses  replaces the Supplement  dated December 1,
1997 and changes the Prospectuses as follows:

1. In the first  paragraph  which  follows  the  table  entitled  "Annual  Trust
Operating  Expenses (as a percentage of average net assets)" on page 1-2, of the
Centennial  Money Market  Trust  Prospectus,  the fifth  sentence is deleted and
replaced with the following:

      On November  21,  1997,  the Manager  withdrew  its  voluntary  waiver and
      amended its Agreement with the Trust.

2. The first two paragraphs in the section entitled "Fees and Expenses" on pages
A-1 to A-2 are deleted and replaced with the following paragraphs:

      o Fees and Expenses.  The management fee is payable monthly to the Manager
under the terms of each Trust's  Agreement and is computed on the average annual
net assets of the  respective  Trust as of the close of business  each day.  The
annual rates  applicable  to Money  Market  Trust are as follows:  0.500% of the
first $250 million of net assets; 0.475% of the next $250 million of net assets;
0.450% of the next $250  million of net assets;  0.425% of the next $250 million
of net assets; 0.400% of the next $250 million of net assets; 0.375% of the next
$250 million of net assets;  0.350% of the next $500 million of net assets;  and
0.325%  of  net  assets  in  excess  of $2  billion.  Furthermore,  the  Manager
guarantees  that the total  expenses of Money  Market  Trust in any fiscal year,
exclusive  of taxes,  interest  and  brokerage  commissions,  and  extraordinary
expenses such as litigation costs,  shall not exceed, and the Manager undertakes
to pay or refund to Money Market Trust any amount by which such  expenses  shall
exceed,  the lesser of (i) 1.5% of the average annual net assets of Money Market
Trust up to $30 million and 1% of its average annual net assets in excess of $30
million; or

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 (ii) 25% of total annual investment income of Money Market Trust.

      The annual rates applicable to Government  Trust are as follows:  0.50% of
the first $250  million of net  assets;  0.475% of the next $250  million of net
assets;  0.45% of the next $250  million of net assets;  0.425% of the next $250
million of net assets; and 0.40% of net assets in excess of $1 billion.

      The annual rates  applicable to Tax Exempt Trust are as follows:  0.50% of
the first $250  million of net  assets;  0.475% of the next $250  million of net
assets;  0.45% of the next $250  million of net assets;  0.425% of the next $250
million of net assets;  0.40% of the next $250 million of net assets;  0.375% of
the next $250  million  of net  assets;  0.35% of the next $500  million  of net
assets and 0.325% of net assets in excess of $2 billion. Furthermore,  under Tax
Exempt  Trust's  Agreement,  when the value of Tax Exempt  Trust's net assets is
less than $1.5  billion,  the annual fee payable to the Manager shall be reduced
by $100,000  based on average net assets  computed daily and paid monthly at the
annual  rates,  but in no event  shall the  annual  fee be less than $0. See the
Statement  of  Additional  Information  for  an  explanation  of  the  Manager's
reimbursement  arrangement  for  the  Trusts  set  forth  in  their  Agreements.
"Investment  Management  Services" in the  Statement of  Additional  Information
contains more complete information about the Agreements,  including a discussion
of expense  arrangements,  and a description of the  exculpation  provisions and
portfolio transactions.

3. Effective June 1, 1998, the second sentence of the fourth paragraph  entitled
"Exchange  Privilege" in the section entitled "Exchanges of Shares" on page A-10
is modified to read as follows:

      The  redemption  proceeds of shares of the Trust,  acquired by exchange of
      Class  A  shares  of an  Eligible  Fund  purchased  subject  to a  Class A
      Contingent Deferred Sales Charge ("CDSC") and redeemed within 18 months of
      the end of the  calendar  month of the initial  purchase of the  exchanged
      shares, will be subject to the Class A CDSC as described in the prospectus
      of that other

                                                      (continued)

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      Eligible Fund.  (A different holding period may apply to shares purchased
      prior to June 1, 1998).


May 20, 1998                                                PS000.006.0598

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