1
 
                         NOTICE OF GUARANTEED DELIVERY
 
                        ENTEX INFORMATION SERVICES, INC.
       OFFER TO EXCHANGE ITS 12 1/2% SENIOR SUBORDINATED NOTES DUE 2006,
    WHICH HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
       FOR ANY AND ALL OF ITS 12 1/2% SENIOR SUBORDINATED NOTES DUE 2006
 
            PURSUANT TO THE PROSPECTUS, DATED                , 1998
 
      THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY TIME, ON
            , UNLESS EXTENDED (THE "EXPIRATION DATE"). TENDERS MAY BE WITHDRAWN
        PRIOR TO 5:00 P.M., NEW YORK CITY TIME, ON THE EXPIRATION DATE.
 
     As set forth in the Prospectus dated                , 1998 (the
"Prospectus") under the caption "The Exchange Offer -- Guaranteed Delivery
Procedures" and the accompanying Letter of Transmittal (the "Letter of
Transmittal") and Instruction 1 thereto, this form, or one substantially
equivalent hereto, must be used to accept the Exchange Offer if certificates
representing the 12 1/2% Senior Subordinated Notes due 2006 (the "Old Notes") of
ENTEX Information Services, Inc., a Delaware corporation (the "Company"), are
not immediately available or if the procedure for book-entry transfer cannot be
completed on a timely basis or time will not permit a Holder's certificates or
other required documents to reach the Exchange Agent on or prior to the
Expiration Date. Such form may be delivered by hand or transmitted by telegram,
telex, facsimile transmission or mail to the Exchange Agent and must include a
guarantee by an Eligible Institution unless such form is submitted on behalf of
an Eligible Institution. Capitalized terms used and not defined herein have the
respective meanings ascribed to them in the Prospectus.
 
                             The Exchange Agent is
 
                              MARINE MIDLAND BANK
 

                                                                            
   BY REGISTERED OR CERTIFIED MAIL:               BY OVERNIGHT COURIER:                          BY HAND:
          MARINE MIDLAND BANK                      MARINE MIDLAND BANK                      MARINE MIDLAND BANK
         140 BROADWAY, LEVEL A                    140 BROADWAY, LEVEL A                    140 BROADWAY, LEVEL A
     NEW YORK, NEW YORK 10005-1180            NEW YORK, NEW YORK 10005-1180            NEW YORK, NEW YORK 10005-1180
 ATTENTION: CORPORATE TRUST OPERATIONS    ATTENTION: CORPORATE TRUST OPERATIONS

 
                                 BY FACSIMILE:
                        (FOR ELIGIBLE INSTITUTIONS ONLY)
 
                                 (212) 658-2292
 
 DELIVERY OF THIS INSTRUMENT TO AN ADDRESS OR TRANSMISSION VIA FACSIMILE NUMBER
        OTHER THAN THE ONES ABOVE WILL NOT CONSTITUTE A VALID DELIVERY.
 
     This form 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.
   2
 
Ladies & Gentlemen:
 
     Upon the terms and subject to the conditions set forth in the Prospectus
and the accompanying Letter of Transmittal, receipt of which is hereby
acknowledged, the undersigned hereby tenders to ENTEX Information Services,
Inc., a Delaware corporation (the "Company"), $          principal amount of Old
Notes, pursuant to the guaranteed delivery procedures set forth in the
Prospectus and accompanying Letter of Transmittal.
 


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         CERTIFICATE NUMBERS OF OLD NOTES                            PRINCIPAL AMOUNT
                  (IF AVAILABLE)                                         TENDERED
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     If Old Notes will be tendered by book-entry transfer to the Depositary
Trust Company, provide account number.
 
                                         Account No.
                                         ---------------------------------------
 
     The undersigned authorizes the Exchange Agent to deliver this Notice of
Guaranteed Delivery to the Company and Marine Midland Bank, as Trustee with
respect to the Old Notes tendered pursuant to the Exchange Offer.
 
     All authority conferred or agreed to be conferred by this Notice of
Guaranteed Delivery shall not be affected by, and shall survive, the death or
incapacity of the undersigned, and every obligation of the undersigned under
this Notice of Guaranteed Delivery shall be binding upon the heirs, executors,
administrators, trustees in bankruptcy, personal and legal representatives,
successors and assigns of the undersigned.
 
                                   SIGN HERE
 
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          SIGNATURE(S) OF REGISTERED HOLDER(S) OR AUTHORIZED SIGNATORY
 
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                        NAME(S) OF REGISTERED HOLDER(S)
                             (PLEASE TYPE OR PRINT)
 
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                                    ADDRESS
 
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                                    ZIP CODE
 
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                         AREA CODE AND TELEPHONE NUMBER

Dated:                   , 1997
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   3
 
                                   GUARANTEE
 
                   (NOT TO BE USED FOR SIGNATURE GUARANTEES)
 
     The undersigned, a member firm of a registered national securities exchange
or of the National Association of Securities Dealers, Inc., or a commercial bank
or trust company having an office in the United States, hereby (a) represents
that the above-named person(s) has a net long position in the Old Notes tendered
hereby within the meaning of Rule 14e-4 under the Securities Exchange Act of
1934, as amended, (b) represents that such tender of Old Notes complies with
Rule 14e-4 and (c) guarantees delivery to the Exchange Agent of certificates
representing the Old Notes tendered hereby, in proper form for transfer, or
confirmation of book-entry transfer of such Old Notes into the Exchange Agent's
account at a Book-Entry Transfer Facility (as defined in the Prospectus), in
each case together with a properly completed and duly executed Letter of
Transmittal with any required signature guarantees and any other documents
required by the Letter of Transmittal, within three New York Stock Exchange
trading days after the date hereof.
 

                                                  
 
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                 NAME OF FIRM                                            TITLE
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             AUTHORIZED SIGNATURE                             NAME (PLEASE TYPE OR PRINT)
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                   ADDRESS                            Dated:                    , 1998
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        AREA CODE AND TELEPHONE NUMBER

 
NOTE: DO NOT SEND CERTIFICATES REPRESENTING OLD NOTES WITH THIS FORM.
      CERTIFICATES FOR OLD NOTES MUST BE SENT WITH YOUR LETTER OF TRANSMITTAL.