SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                 SCHEDULE 13E-4

                          ISSUER TENDER OFFER STATEMENT
                      (PURSUANT TO SECTION 13(E)(1) OF THE
                        SECURITIES EXCHANGE ACT OF 1934)

                       (AMENDMENT NO. 2 - FINAL AMENDMENT)

                                 HYBRIDON, INC.
                  (NAME OF ISSUER AND PERSON FILING STATEMENT)

                   9% CONVERTIBLE SUBORDINATED NOTES DUE 2004
                       (TITLE OF EACH CLASS OF SECURITIES)

                 44860M-AA-6; -AB-4; -AC-2; -AD-0; -AE-8; -AF-5
                   (CUSIP NUMBERS OF EACH CLASS OF SECURITIES)

                            E. ANDREWS GRINSTEAD, III
                 CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                               620 MEMORIAL DRIVE
                               CAMBRIDGE, MA 02139
                                 (617) 528-7000
            (NAME, ADDRESS AND TELEPHONE NUMBER OF PERSON AUTHORIZED
             TO RECEIVE NOTICES AND COMMUNICATIONS ON BEHALF OF THE
                            PERSON FILING STATEMENT)

                                  WITH COPY TO:

                              MONICA C. LORD, ESQ.
                        KRAMER, LEVIN, NAFTALIS & FRANKEL
                                919 THIRD AVENUE
                            NEW YORK, NEW YORK 10022
                                 (212) 715-9100

                                FEBRUARY 6, 1998
     (DATE TENDER OFFER FIRST PUBLISHED, SENT OR GIVEN TO SECURITY HOLDERS)

                            CALCULATION OF FILING FEE
 TRANSACTION VALUATION (1)                           AMOUNT OF FILING FEE (2)
 -------------------------                           ------------------------
        $51,594,664                                           $10,319

(1)  Solely for the  purpose of  calculating  the  filing fee and,  as  computed
pursuant to Section 13(e)(3) of the Securities Exchange Act of 1934, as amended,
and Rule  0-11(b)(1)  thereunder,  the  transaction  value equals the  aggregate
principal  amount of and accrued but unpaid interest on the securities  proposed
to be  exchanged  pursuant to the Offer  described  in the Offer to Exchange and
Amendment thereto filed as Exhibits hereto.

(2)  Represents 1/50th of 1% of the transaction value as calculated above.

[_] Check box if any part of the fee is offset as  provided  by Rule  0-11(a)(2)
and  identify  the filing with which the  offsetting  fee was  previously  paid.
Identify the previous filing by registration  statement  number,  or the Form or
Schedule and the date of its filing.

Amount Previously Paid:                 Filing Party: 
                       -----------                   -----------------------

Form or Registration No.:               Date Filed: 
                         ---------                   -----------------------




         This  Amendment  No. 2, the final  amendment,  amends the Issuer Tender
Offer Statement on Schedule  13E-4,  dated as of February 6, 1998 and as amended
by Amendment No. 1 thereto (together,  the "Schedule 13E-4"), of Hybridon,  Inc.
("Hybridon" or the "Company").  Capitalized  terms not otherwise  defined herein
shall have the  meanings  set forth in the Offer to Exchange  dated  February 6,
1998, as amended (the "Offer to Exchange").

TERMINATION OF ISSUER TENDER OFFER.

          The Offer terminated at 12:00 a.m., New York City time, on May 4, 1998
          (the  "Expiration  Date").  As of the Expiration  Date, the holders of
          approximately  $48.6  million  in  principal  amount  of 9% Notes  had
          tendered such notes pursuant to the Offer, leaving  approximately $1.4
          million in principal amount of 9% Notes  outstanding.  On May 5, 1998,
          the Equity  Conditions were satisfied and the Company  accepted the 9%
          Notes  tendered  in the Offer in  exchange  for shares of  Alternative
          Series A Preferred Stock and Alternative Exchange Warrants to purchase
          Common Stock,  according to the terms of the Offer as set forth in the
          Schedule 13E-4 and the exhibits thereto.


                                        2



                                    SIGNATURE


After due inquiry and to the best of my knowledge and belief, I certify that the
information set forth in this Amendment to Schedule 13E-4 is true,  complete and
correct.

Dated:  May 18, 1998

                                          HYBRIDON, INC.



                                         By: /s/ E. Andrews Grinstead III
                                             ----------------------------
                                         Name: E. Andrews Grinstead III
                                         Title: Chairman, President and
                                                Chief Executive Officer



                                        3