SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM 8-K


                                 CURRENT REPORT


                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


                Date of Report (Date of earliest event reported)


                                October 16, 1997


                        TRUSTED INFORMATION SYSTEMS, INC.
               (Exact Name of Registrant as Specified in Charter)


            Delaware                  000-21067          51-0375640
   (State of Incorporation)   (Commission File Number)  (IRS Employer
                                                         Identification No.)



                          3060 Washington Road (Rt. 97)
                            Glenwood, Maryland 21738
               (Address of principal executive offices) (Zip Code)


                                 (301) 854-6889
                         (Registrant's telephone number)




                                       1
<PAGE>
 

Item 2.     Acquisition or Disposition of Assets.

     On October  13,  1997,  the  shareholders  of Haystack  Laboratories,  Inc.
("Haystack") approved the merger between Haystack and Trusted Acquisitions, Inc.
("Merger Sub"), a Delaware corporation and a wholly-owned  subsidiary of Trusted
Information  Systems,  Inc.  ("TIS"),  pursuant to the terms of an Agreement and
Plan of Merger,  dated as of October 3,  1997,  by and among  Haystack,  TIS and
Merger Sub (the "Merger  Agreement") and, effective October 16, 1997, Merger Sub
has been merged with and into Haystack. As provided in the Merger Agreement, TIS
will issue an aggregate of two million, one hundred five thousand,  four hundred
ninety four  (2,105,494)  shares of TIS Common  Stock for all shares of Haystack
Common Stock outstanding  immediately prior to the effective time of the merger,
including  shares issued upon the exercise of certain stock options and warrants
outstanding immediately prior to the effective time of the merger. Each share of
Haystack's  Common Stock was converted  into the right to receive  0.236330 of a
share of TIS Common Stock.

     TIS will account for the  acquisition  under the pooling of interest method
of accounting.

     Before the Merger,  Haystack developed and marketed its  Stalker(registered
trademark)  and   WebStalker(registered   trademark)   intrusion  detection  and
monitoring software products.  TIS intends to integrate the existing Stalker and
WebStalker software technology with TIS's Gauntlet(registered  trademark) family
of  products  to  provide  customers  with a single  firm for  multi-dimensional
solutions  that  prevent,  detect and respond to threats  from both  outside and
inside a company's network.




                                       2
<PAGE>




Item 7.     Financial Statements and Exhibits.

(a)      Financial  Statements of Business Acquired.  The financial statements
of Haystack will be provided within sixty (60) days on Form 8-A.

(b)      Pro Forma  Financial  Information.  Pro forma  financial  information
will be provided  within sixty (60)days on Form 8-A.

(c)      Exhibits.

         Exhibit No.                                 Description

            2                                Agreement and Plan of Merger among
                                             Trusted Information Systems, Inc.,
                                             Trusted Acquisitions, Inc. and
                                             Haystack Laboratories, Inc., dated
                                             as of October 3, 1997.

         99                                   Press Release of Trusted
                                              Information Systems, Inc., dated
                                              October 3, 1997.




                                       3
<PAGE>



                                   SIGNATURES

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned thereunto duly authorized.


Date:    October 24, 1997              TRUSTED INFORMATION SYSTEMS, INC.



                                       By:   /s/ Stephen T. Walker
                                                 Stephen T. Walker
                                       President and Chief Executive Officer


                                       4
<PAGE>





                        TRUSTED INFORMATION SYSTEMS, INC.

                                    FORM 8-K

                                  EXHIBIT INDEX


Exhibit No.                         Description

   2                                Agreement and Plan of Merger among
                                    Trusted Information Systems, Inc.,
                                    Trusted Acquisitions, Inc. and
                                    Haystack Laboratories, Inc., dated
                                    as of October 3, 1997

   99                               Press Release of Trusted Information
                                    Systems, Inc. dated October 3, 1997.


                                       5
<PAGE>
[{"type": "8-K", "sequence": "1", "description": "MERGER WITH HAYSTACKS LABORATORIES, INC.", "secsgml_size_bytes": 5299}]
{"company-data": {"conformed-name": "TRUSTED INFORMATION SYSTEMS INC", "cik": "0001013355", "assigned-sic": "7372", "irs-number": "521281786", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "000-21067", "film-number": "97700783"}, "business-address": {"street1": "3060 WASHINGTON ROAD", "city": "GLENWOOD", "state": "MD", "zip": "21738", "phone": "3018546889"}, "mail-address": {"street1": "3060 WASHINGTON ROAD", "city": "GLENWOOD", "state": "MD", "zip": "21738"}}
SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                Date of Report (Date of earliest event reported)

                                October 16, 1997

                        TRUSTED INFORMATION SYSTEMS, INC.
               (Exact Name of Registrant as Specified in Charter)

            Delaware                  000-21067          51-0375640
   (State of Incorporation)   (Commission File Number)  (IRS Employer
                                                         Identification No.)

                          3060 Washington Road (Rt. 97)
                            Glenwood, Maryland 21738
               (Address of principal executive offices) (Zip Code)

                                 (301) 854-6889
                         (Registrant's telephone number)

                                       1
Item 2.     Acquisition or Disposition of Assets.

     On October  13,  1997,  the  shareholders  of Haystack  Laboratories,  Inc.
("Haystack") approved the merger between Haystack and Trusted Acquisitions, Inc.
("Merger Sub"), a Delaware corporation and a wholly-owned  subsidiary of Trusted
Information  Systems,  Inc.  ("TIS"),  pursuant to the terms of an Agreement and
Plan of Merger,  dated as of October 3,  1997,  by and among  Haystack,  TIS and
Merger Sub (the "Merger  Agreement") and, effective October 16, 1997, Merger Sub
has been merged with and into Haystack. As provided in the Merger Agreement, TIS
will issue an aggregate of two million, one hundred five thousand,  four hundred
ninety four  (2,105,494)  shares of TIS Common  Stock for all shares of Haystack
Common Stock outstanding  immediately prior to the effective time of the merger,
including  shares issued upon the exercise of certain stock options and warrants
outstanding immediately prior to the effective time of the merger. Each share of
Haystack's  Common Stock was converted  into the right to receive  0.236330 of a
share of TIS Common Stock.

     TIS will account for the  acquisition  under the pooling of interest method
of accounting.

     Before the Merger,  Haystack developed and marketed its  Stalker(registered
trademark)  and   WebStalker(registered   trademark)   intrusion  detection  and
monitoring software products.  TIS intends to integrate the existing Stalker and
WebStalker software technology with TIS's Gauntlet(registered  trademark) family
of  products  to  provide  customers  with a single  firm for  multi-dimensional
solutions  that  prevent,  detect and respond to threats  from both  outside and
inside a company's network.

                                       2
Item 7.     Financial Statements and Exhibits.

(a)      Financial  Statements of Business Acquired.  The financial statements
of Haystack will be provided within sixty (60) days on Form 8-A.

(b)      Pro Forma  Financial  Information.  Pro forma  financial  information
will be provided  within sixty (60)days on Form 8-A.

(c)      Exhibits.

         Exhibit No.                                 Description

            2                                Agreement and Plan of Merger among
                                             Trusted Information Systems, Inc.,
                                             Trusted Acquisitions, Inc. and
                                             Haystack Laboratories, Inc., dated
                                             as of October 3, 1997.

         99                                   Press Release of Trusted
                                              Information Systems, Inc., dated
                                              October 3, 1997.

                                       3
SIGNATURES

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned thereunto duly authorized.

Date:    October 24, 1997              TRUSTED INFORMATION SYSTEMS, INC.

                                       By:   /s/ Stephen T. Walker
                                                 Stephen T. Walker
                                       President and Chief Executive Officer

                                       4
TRUSTED INFORMATION SYSTEMS, INC.

                                    FORM 8-K

                                  EXHIBIT INDEX

Exhibit No.                         Description

   2                                Agreement and Plan of Merger among
                                    Trusted Information Systems, Inc.,
                                    Trusted Acquisitions, Inc. and
                                    Haystack Laboratories, Inc., dated
                                    as of October 3, 1997

   99                               Press Release of Trusted Information
                                    Systems, Inc. dated October 3, 1997.

                                       5