WASHINGTON, D.C. 20549

                                  FORM 10-Q/A

                          AMENDMENT NO. 1 TO FORM 10-Q

                OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the Quarterly Period Ended: June 30, 1997     Commission File Number 0-27352

                                   Hybridon, Inc.
               (Exact name of registrant as specified in its charter)

           Delaware                                  04-3072298
           --------                                  ----------
(State or other jurisdiction of       (I.R.S. Employer Identification Number)
organization or incorporation)

                                 620 Memorial Drive
                                 Cambridge, MA 02139
            (Address of principal executive offices, including zip code)

                                   (617) 528-7000
                (Registrant's telephone number, including area code)

Indicate by check mark whether the registrant (1) has filed all reports to be
filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the
preceding 12 months (or for such shorter period that the registrant was required
to file such reports), and (2) has been subject to such filing requirements for
the past 90 days.

                             YES  X      NO
                                ------     ------

Indicate the number of shares outstanding of each of the issuer's classes of
common stock, as of the latest practicable date.

Common Stock, par value $.001 per share                      25,260,252
- ---------------------------------------                      ----------
               Class                             Outstanding as of July 31, 1997

      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.

                                    HYBRIDON, INC.

August 15, 1997                     /s/ E. Andrews Grinstead III
- ---------------                     ----------------------------
Date                                E. Andrews Grinstead, III
                                    Chairman, President and Chief Executive
                                    Officer (Principal Executive Officer)

August 15, 1997                     /s/ Anthony J. Payne
- ---------------                     --------------------
Date                                Anthony J. Payne
                                    Senior Vice President of Finance and
                                    Administration and Chief Financial Officer
                                    (Principal Financial and Accounting Officer)
                                 HYBRIDON, INC.

                                  EXHIBIT INDEX

Exhibit No.                      Description
- ----------                       -----------
*+10.1     Amendment No. 1 to License Agreement, dated as February 21, 1990 and
           restated as of September 8, 1993, by and between the Worcester 
           Foundation for Biomedical Research, Inc. and the Company, dated as
           of November 26, 1996.

 +10.2     Letter Agreement dated May 12, 1997 between the Company and Pillar
           S.A. amending the Consulting Agreement dated as of March 1, 1994
           between the Company and Pillar S.A..

 +10.3     Amendment dated July 15, 1997 to the Series G Convertible Preferred
           Stock and Warrant Purchase Agreement dated as of September 9, 1994
           among the Company and certain purchasers, as amended.
  10.4     Sixth Amendment to the lease dated April 1997 between the Company and
           Charles River Building Limited Partnership for space located at 620
           Memorial Drive, Cambridge, Massachusetts.

 +11       Computation of Net Loss Per Common Share.

 +27       Financial Data Schedule (EDGAR)

 +99       Pages 39-48 of the Company's Annual Report on Form 10-K for the 
           period ended December 31, 1996 (which is not deemed to be filed
           except to the extent that portions thereof are expressly incorporated
           by reference herein).

*          Confidential treatment requested as to certain portions of exhibit,
           which portions have been omitted and filed separately with the 

+          Incorporated by reference to Exhibits to the Registrant's Quarterly
           Report on Form 10-Q for the three months ended June 30, 1997, filed 
           with the Commission on August 14, 1997

                                                                   EXHIBIT 10.4

                           SIXTH AMENDMENT TO LEASE

   This Sixth Amendment to Lease is entered into by and between Charles River
Building Limited Partnership, a Delaware limited partnership (the "Landlord")
and Hybridon, Inc., a Delaware corporation (the "Tenant") as of April __, 1997.
Reference is hereby made to that certain Lease between Landlord and Tenant
dated February 4, 1994, as amended by a First Amendment to Lease dated as of
November 30, 1995, a Second Amendment to Lease dated as of February 23, 1996, a
Third Amendment to Lease dated as of February 28, 1996, a Fourth Amendment to
Lease dated July 25, 1996 and a Fifth Amendment to Lease dated March 14, 1997
(as affected by this Fifth Amendment to Lease, the "Lease").

   WHEREAS, the Tenant has elected to exercise the Equity Investment Option (as
defined in the Lease); and

   WHEREAS, Landlord and Tenant have agreed that the Building (as defined in
the Lease) contains 91,500 rentable square feet; and

   WHEREAS, Landlord and Tenant have agreed to extend the initial Term (as
defined in the Lease) for an additional five years; and

   WHEREAS, Landlord and Tenant have agreed that the Commencement Date (as
defined in the Lease) was February 1, 1997;

   NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Landlord and Tenant hereby agree
as of the date hereof that the Lease is amended as follows:

   1.  The recitals set forth above are hereby incorporated herein.

   2.  Capitalized terms used herein and not otherwise defined shall have the 
       meanings ascribed thereto in the Lease.

   3.  The definitions set forth in Section 1.1 of the Lease for the term set
       forth below are hereby deleted and replaced with the following:

       Term:                    Fifteen (15) years, commencing on the
                                Commencement Date, with three (3) five (5) year 
                                options to extend, as set forth in Section 2.3

       Annual Fixed Rent Rate:  During the original Term, for the five years
                                commencing on the Commencement Date,
                                Thirty-Seven and 79/100 Dollars ($37.79) per

                                annum per rentable square foot of the Building;
                                for the next five years commencing on the fifth
                                anniversary of the Commencement Date, Forty-Two
                                and 73/100 Dollars ($42.73) per annum per
                                rentable square foot of the Building; for the
                                next five years commencing on the tenth
                                anniversary of the Commencement Date,
                                Forty-Seven and 00/100 Dollars ($47.00) per
                                annum per rentable square foot of the Building;
                                the Annual Fixed Rent Rate during each
                                extension Term under this Lease shall be that
                                described in Section 2.3. The parties hereby
                                agree that the Building contains 91,500
                                rentable square feet. The parties further agree
                                that the foregoing Annual Fixed Rent Rate       
                                refects the adjustment required under the Lease
                                pursuant to the election by the Tenant of the
                                Equity Investment Option and that, therefore,
                                no further adjustment with respect thereto
                                shall be required.
       Commencement Date:       February 1, 1997

   4.  To the extent not amended hereby, the Lease is hereby ratified and


     EXECUTED as a sealed instrument as of the date first above written.


                                 CHARLES RIVER BUILDING LIMITED PARTNERSHIP, a
                                 Delaware limited partnership

                                 By:  Pillar Development and Management, Inc., a
                                      Delaware corporation

                                      By: /s/ Peter Morris
                                         Name: Peter Morris
                                         Title: General Partner, Pillar
                                                Development and Management Inc.


                                 HYBRIDON, INC., a Delaware corporation

                                      By: /s/ Anthony J. Payne
                                         Name: Anthony J. Payne
                                         Title: Chief Financial Officer