
<PAGE>
 
                         NOTICE OF GUARANTEED DELIVERY
                                      FOR
                       TENDER OF SHARES OF COMMON STOCK
                                      OF
 
                               FORUM GROUP, INC.
 
   This form, or a form substantially equivalent to this form, must be used to
accept the Offer (as defined below) if the certificates representing shares of
common stock, without par value, of Forum Group, Inc. (the "Shares") are not
immediately available or if the procedure for book-entry transfer cannot be
completed on a timely basis or if time will not permit all required documents
to reach the Depositary at or prior to the expiration of the Offer. Such form
may be delivered by hand or transmitted by telegram, facsimile transmission or
mail to the Depositary. See Section 3 of the Offer to Purchase.
 
                       The Depositary for the Offer is:
 
                    FIRST CHICAGO TRUST COMPANY OF NEW YORK
 
                                 By Facsimile         By Hand or By Overnight
         By Mail:               Transmission:                 Courier:
 
    Tenders & Exchanges         (201) 222-4720          Tenders & Exchanges
P.O. Box 2559--Suite 4660--           or               14 Wall Street, Suite
            FGI                 (201) 222-4721               4680--FGI
  Jersey City, New Jersey                            New York, New York 10005
         07303-2559             
 
        Confirm Receipt of Notice of Guaranteed Delivery by Telephone:
 
                                (201) 222-4707
 
                               ----------------
 
   DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY TO AN ADDRESS OTHER THAN AS
SET FORTH ABOVE, OR TRANSMISSION OF INSTRUCTIONS VIA A FACSIMILE NUMBER OTHER
THAN AS LISTED ABOVE, WILL NOT CONSTITUTE A VALID DELIVERY.
 
  This Notice of Guaranteed Delivery is not to be used to guarantee
signatures. If a signature on a Letter of Transmittal is required to be
guaranteed by an "Eligible Institution" under the instructions thereto, such
signature guarantee must appear in the applicable space provided in the
signature box on the Letter of Transmittal.
<PAGE>
 
Ladies and Gentlemen:
 
  The undersigned hereby tenders to FG Acquisition Corp. (the "Purchaser"), an
Indiana corporation and a wholly owned indirect subsidiary of Marriott
International, Inc., a Delaware corporation, upon the terms and subject to the
conditions set forth in the Offer to Purchase, dated February 23, 1996 (the
"Offer to Purchase"), and the related Letter of Transmittal (which together
constitute the "Offer"), receipt of which is hereby acknowledged, the number
of Shares indicated below pursuant to the guaranteed delivery procedure set
forth in Section 3 of the Offer to Purchase.
 
---------------------------------------   --------------------------------------

  Number of Shares: _________________       Name(s) of Record Holder(s):
 
  Share Certificate Numbers (if             ___________________________________
  available):                               
                                            ___________________________________
  ___________________________________              Please Type or Print       

  ___________________________________       Address(es) _______________________

                                            ___________________________________
  If Shares will be delivered by                                       Zip Code
  book-entry transfer, check one box:       
                                            Area Code and Telephone Number:
  [_] The Depository Trust Company
                                            ___________________________________
  [_] Midwest Securities Trust    
      Company                               ___________________________________
 
  [_] Philadelphia Depository Trust         ___________________________________
      Company                      
                                            ___________________________________
  Account Number ____________________                   Signature(s)
                                     
  Dated: _______________ , 1996             Dated: _______________ , 1996

---------------------------------------   --------------------------------------
 
                                   GUARANTEE
 
                   (NOT TO BE USED FOR SIGNATURE GUARANTEE)
 
  The undersigned, a member firm of a registered national securities exchange,
a member of the National Association of Securities Dealers, Inc. or a
commercial bank or trust company having an office or correspondent in the
United States (each, an "Eligible Institution"), hereby guarantees that either
the certificates representing the Shares tendered hereby in proper form for
transfer, or timely confirmation of a book-entry transfer of such Shares into
the Depositary's account at The Depository Trust Company, the Midwest
Securities Trust Company or the Philadelphia Depository Trust Company
(pursuant to guaranteed delivery procedures set forth in Section 3 of the
Offer to Purchase), together with a properly completed and duly executed
Letter of Transmittal (or manually signed facsimile thereof) with any required
signature guarantee and any other required documents, will be received by the
Depositary at one of its addresses set forth above within three (3) Nasdaq
Small Cap Market trading days after the date of execution hereof.
 
  The Eligible Institution that completes this form must communicate the
guarantee to the Depositary and must deliver the Letter of Transmittal and
certificates for Shares to the Depositary within the time period shown herein.
Failure to do so could result in a financial loss to such Eligible
Institution.
 
Name of Firm: _______________________     _____________________________________
                                                   Authorized Signature
Address: ____________________________
                                          Name: _______________________________
         ____________________________              Please Type or Print
                             Zip Code
                                          Title: ______________________________
Area Code and                        
Telephone Number: ___________________     Dated: _______________________ , 1996
 
NOTE: DO NOT SEND CERTIFICATES FOR SHARES WITH THIS NOTICE OF GUARANTEED
      DELIVERY. CERTIFICATES FOR SHARES ARE TO BE DELIVERED WITH THE LETTER OF
      TRANSMITTAL.
 
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