content: <PAGE>
  
                         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
  
                                    June 1, 2000
                                ____________________
  
                  Date of Report (Date of earliest event reported)
  
                                SIEBEL SYSTEMS, INC.
                                ____________________
  
               (Exact name of registrant as specified in its charter)
  
             Delaware                        0-20725              94-3187233
          _______________                _______________        _______________
  
  (State or other jurisdiction of          (Commission          (I.R.S. Employer
          incorporation                    File Number)        Identification No.)
  
                              1855 South Grant Street
                                San Mateo, CA  94402
                                ____________________
  
                      (Address of principal executive offices)
  
                                   (650) 295-5000
                                ____________________
  
                (Registrant's telephone number, including area code)
  <PAGE>
  
  Item 2.  Acquisition or Disposition of Assets.
  
       Effective May 17, 2000, OS Acquisition Corp., a Delaware corporation
  ("Merger Sub"), which was a wholly-owned subsidiary of Siebel Systems, Inc., a
  Delaware corporation ("Siebel"), was merged (the "Merger") with and into
  OpenSite Technologies Inc., a Delaware corporation ("OpenSite"), pursuant to an
  Agreement and Plan of Merger and Reorganization (the "Reorganization Agreement")
  dated April 5, 2000 by and among Siebel, Merger Sub, OpenSite and Alan Taetle,
  as Stockholders' Agent.  The description contained in this Item 2 of the
  transactions consummated pursuant to the terms and conditions of the
  Reorganization Agreement is qualified in its entirety by reference to the full
  text of the Reorganization Agreement, a copy of which is attached to this Report
  as Exhibit 2.1.
  
       In the Merger, each then-outstanding share of common stock ($.01 par value)
  of OpenSite was converted into the right to receive the "Applicable Fraction" of
  a share of common stock of Siebel.  The Applicable Fraction is the fraction
  having a numerator equal to 3,935,599 and a denominator equal to the sum of (i)
  the aggregate number of shares of common stock of OpenSite outstanding
  immediately prior to the effective time of the Merger (the "Effective Time")
  (including any shares that are subject to a repurchase option or risk of
  forfeiture under any restricted stock purchase or other agreement), plus (ii)
  the aggregate number of shares of common stock of OpenSite purchasable under or
  otherwise subject to all options, warrants or convertible debentures to purchase
  shares of OpenSite common stock outstanding immediately prior to the Effective
  Time (including all shares of OpenSite common stock that may be ultimately
  purchased under options to purchase shares of OpenSite common stock that are
  unvested or are otherwise not then exercisable). Pursuant to the Reorganization
  Agreement, Siebel assumed outstanding options to acquire common stock of
  OpenSite in accordance with the terms of such options. In no event will Siebel
  be required to issue in excess of 3,935,599 shares of its common stock in
  respect of the securities of OpenSite. No fractional shares of Siebel common
  stock will be issued in connection with the Merger. In lieu thereof, any holder
  of OpenSite common stock who would otherwise have been entitled to receive
  fractional shares of Siebel common stock will be paid an amount based on the
  value of a whole share of $131.7875 (rounded to the nearest whole cent) without
  interest. At the Effective Time, Merger Sub ceased to exist and OpenSite, as the
  surviving corporation in the Merger, became a wholly-owned subsidiary of Siebel.
  
       The Merger is intended to qualify as a tax-free reorganization under the
  Internal Revenue Code of 1986, as amended, and is expected to be accounted for
  as a pooling-of-interests.  Copies of the press releases announcing the
  intention to undertake the Merger and the consummation of the Merger are
  attached hereto as Exhibits 99.1 and 99.2.
  
       OpenSite is a market leader in Web-based dynamic commerce solutions.
  OpenSite provides a wide range of software products, services and outsourced
  solutions that allow businesses to utilize a variety of pricing options, such as
  forward auctions, reverse auctions, auction networks, cross-auction portals and
  exchanges, on their Web sites.
  
       Siebel is the world's leading supplier of eBusiness applications software.
  Siebel provides an integrated family of eBusiness application software enabling
  multichannel sales, marketing and customer service systems to be deployed over
  the Web, call centers, field, reseller channels, retail and dealer networks.
  Siebel's sales and service facilities are deployed locally in more than 28
  countries.
  
  Item 7.    Financial Statements, Pro Forma Financial Information and Exhibits.
  
             (a)  Financial Statements of Business Acquired.
  
             Not applicable.
  <PAGE>
  
             (b)  Pro Forma Financial Information
  
             Not applicable.
  
             (c)  Exhibits
  
             The following Exhibits are filed as part of this report:
  
          2.1  Agreement and Plan of Merger and Reorganization, dated April 5,
               2000, by and among Siebel, Merger Sub, OpenSite and Alan Taetle, as
               Stockholders' Agent. The disclosure schedule of OpenSite and
               certain exhibits to the agreement are omitted. The registrant
               agrees to furnish supplementally copies of such schedule and
               exhibits to the Commission upon request.
  
         99.1  Press Release of Siebel dated April 18, 2000.
  
         99.2  Press Release of Siebel dated May 18, 2000.
  <PAGE>
  
                                     SIGNATURE
  
       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 hereunto duly authorized.
  
                                      Siebel Systems, Inc.
  Date:  May 31, 2000
  
                                          By:   /s/ Howard H. Graham
                                              -------------------------------
                                                Howard H. Graham
                                                Senior Vice President,
                                                Finance and Administration
                                                and Chief Financial Officer
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text: 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
  
                                    June 1, 2000
                                ____________________
  
                  Date of Report (Date of earliest event reported)
  
                                SIEBEL SYSTEMS, INC.
                                ____________________
  
               (Exact name of registrant as specified in its charter)
  
             Delaware                        0-20725              94-3187233
          _______________                _______________        _______________
  
  (State or other jurisdiction of          (Commission          (I.R.S. Employer
          incorporation                    File Number)        Identification No.)
  
                              1855 South Grant Street
                                San Mateo, CA  94402
                                ____________________
  
                      (Address of principal executive offices)
  
                                   (650) 295-5000
                                ____________________
  
                (Registrant's telephone number, including area code)
  Item 2.  Acquisition or Disposition of Assets.
  
       Effective May 17, 2000, OS Acquisition Corp., a Delaware corporation
  ("Merger Sub"), which was a wholly-owned subsidiary of Siebel Systems, Inc., a
  Delaware corporation ("Siebel"), was merged (the "Merger") with and into
  OpenSite Technologies Inc., a Delaware corporation ("OpenSite"), pursuant to an
  Agreement and Plan of Merger and Reorganization (the "Reorganization Agreement")
  dated April 5, 2000 by and among Siebel, Merger Sub, OpenSite and Alan Taetle,
  as Stockholders' Agent.  The description contained in this Item 2 of the
  transactions consummated pursuant to the terms and conditions of the
  Reorganization Agreement is qualified in its entirety by reference to the full
  text of the Reorganization Agreement, a copy of which is attached to this Report
  as Exhibit 2.1.
  
       In the Merger, each then-outstanding share of common stock ($.01 par value)
  of OpenSite was converted into the right to receive the "Applicable Fraction" of
  a share of common stock of Siebel.  The Applicable Fraction is the fraction
  having a numerator equal to 3,935,599 and a denominator equal to the sum of (i)
  the aggregate number of shares of common stock of OpenSite outstanding
  immediately prior to the effective time of the Merger (the "Effective Time")
  (including any shares that are subject to a repurchase option or risk of
  forfeiture under any restricted stock purchase or other agreement), plus (ii)
  the aggregate number of shares of common stock of OpenSite purchasable under or
  otherwise subject to all options, warrants or convertible debentures to purchase
  shares of OpenSite common stock outstanding immediately prior to the Effective
  Time (including all shares of OpenSite common stock that may be ultimately
  purchased under options to purchase shares of OpenSite common stock that are
  unvested or are otherwise not then exercisable). Pursuant to the Reorganization
  Agreement, Siebel assumed outstanding options to acquire common stock of
  OpenSite in accordance with the terms of such options. In no event will Siebel
  be required to issue in excess of 3,935,599 shares of its common stock in
  respect of the securities of OpenSite. No fractional shares of Siebel common
  stock will be issued in connection with the Merger. In lieu thereof, any holder
  of OpenSite common stock who would otherwise have been entitled to receive
  fractional shares of Siebel common stock will be paid an amount based on the
  value of a whole share of $131.7875 (rounded to the nearest whole cent) without
  interest. At the Effective Time, Merger Sub ceased to exist and OpenSite, as the
  surviving corporation in the Merger, became a wholly-owned subsidiary of Siebel.
  
       The Merger is intended to qualify as a tax-free reorganization under the
  Internal Revenue Code of 1986, as amended, and is expected to be accounted for
  as a pooling-of-interests.  Copies of the press releases announcing the
  intention to undertake the Merger and the consummation of the Merger are
  attached hereto as Exhibits 99.1 and 99.2.
  
       OpenSite is a market leader in Web-based dynamic commerce solutions.
  OpenSite provides a wide range of software products, services and outsourced
  solutions that allow businesses to utilize a variety of pricing options, such as
  forward auctions, reverse auctions, auction networks, cross-auction portals and
  exchanges, on their Web sites.
  
       Siebel is the world's leading supplier of eBusiness applications software.
  Siebel provides an integrated family of eBusiness application software enabling
  multichannel sales, marketing and customer service systems to be deployed over
  the Web, call centers, field, reseller channels, retail and dealer networks.
  Siebel's sales and service facilities are deployed locally in more than 28
  countries.
  
  Item 7.    Financial Statements, Pro Forma Financial Information and Exhibits.
  
             (a)  Financial Statements of Business Acquired.
  
             Not applicable.
  (b)  Pro Forma Financial Information
  
             Not applicable.
  
             (c)  Exhibits
  
             The following Exhibits are filed as part of this report:
  
          2.1  Agreement and Plan of Merger and Reorganization, dated April 5,
               2000, by and among Siebel, Merger Sub, OpenSite and Alan Taetle, as
               Stockholders' Agent. The disclosure schedule of OpenSite and
               certain exhibits to the agreement are omitted. The registrant
               agrees to furnish supplementally copies of such schedule and
               exhibits to the Commission upon request.
  
         99.1  Press Release of Siebel dated April 18, 2000.
  
         99.2  Press Release of Siebel dated May 18, 2000.
  SIGNATURE
  
       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 hereunto duly authorized.
  
                                      Siebel Systems, Inc.
  Date:  May 31, 2000
  
                                          By:   /s/ Howard H. Graham
                                              -------------------------------
                                                Howard H. Graham
                                                Senior Vice President,
                                                Finance and Administration
                                                and Chief Financial Officer