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                                                             EXHIBIT (a)(3)(iii)

                            [VAN KAMPEN LETTERHEAD]

July 21, 2000

RE: VAN KAMPEN SENIOR FLOATING RATE FUND
     Commencement of Tender Offer

To Our Dealer Friends:

     As you may be aware, it is the policy of the Board of Trustees of Van
Kampen Senior Floating Rate Fund (the "Trust") to consider on a quarterly basis
whether to make a tender offer for common shares of the Trust. We are pleased to
announce that the Board has authorized the Trust's tenth quarterly tender offer
commencing today, July 21, 2000, for the purpose of attempting to provide
liquidity to its shareholders. The commencement of the tender offer was
announced in the Wall Street Journal today.

     The Trust is offering to purchase up to 37,624,602 of its common shares at
a price equal to the net asset value per common share of the Trust determined as
of 5:00 P.M. Eastern Standard Time on the expiration date of the offer. The
offer is scheduled to terminate as of 12:00 Midnight Eastern Standard Time on
August 18, 2000, the expiration date of the offer (unless extended). An "Early
Withdrawal Charge" will be imposed on most common shares accepted for payment
that have been held for less than one year.

     Terms and conditions of the tender offer are contained in the Trust's Offer
to Purchase dated July 21, 2000, and the related Letter of Transmittal, copies
of which are available to you upon request.

     Should you have any questions regarding the tender offer, please contact
Van Kampen's Investor Services Department at 1-800-421-5666.

Sincerely,

VAN KAMPEN FUNDS INC.

                                                                 10 SFR003-07/00