As filed with the Securities and Exchange Commission on May 28, 2004

Registration No. 333-_____

SECURITIES AND EXCHANGE COMMISSION

FORM S-8

REGISTRATION STATEMENT UNDER
THE SECURITIES ACT OF 1933

Hybridon, Inc.

1995 Director Stock Option Plan
(Full Title of the Plan)

Stephen R. Seiler
Chief Executive Officer
Hybridon, Inc.
345 Vassar Street
Cambridge, Massachusetts 02139
(Name and Address of Agent For Service)
(617) 679-5500
(Telephone Number, Including Area Code, of Agent For Service)

CALCULATION OF REGISTRATION FEE

STATEMENT OF INCORPORATION BY REFERENCE

     This Registration Statement on Form S-8 is filed to register the offer and sale of an additional 400,000 shares of the Registrant’s common stock, $0.001 par value per share, to be issued under the Registrant’s 1995 Director Stock Option Plan. This Registration Statement incorporates by reference the contents of the registration statement on form S-8, File No. 333-03902, filed by the Registrant on April 23, 1996, relating to the Registrant’s 1995 Director Stock Option Plan.

     Item 1. Interests of Named Experts and Counsel.

     Hale and Dorr LLP has opined as to the legality of the securities being offered by this registration statement.

     The Exhibit Index immediately preceding the exhibits is incorporated herein by reference.

- 1 -

SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Cambridge, Massachusetts, on this 28th day of May 2004.

POWER OF ATTORNEY AND SIGNATURES

     We, the undersigned officers and directors of Hybridon, Inc. hereby severally constitute and appoint Stephen R. Seiler and Robert G. Andersen, and each of them singly, our true and lawful attorneys with full power to them, and each of them singly, to sign for us and in our names in the capacities indicated below, the registration statement on Form S-8 filed herewith and any and all subsequent amendments to said registration statement, and generally to do all such things in our names and on our behalf in our capacities as officers and directors to enable Hybridon, Inc. to comply with the provisions of the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission, hereby ratifying and confirming our signatures as they may be signed by our said attorneys, or any of them, to said registration statement and any and all amendments thereto.

     Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the dates indicated.

- 2 -

- 3 -

INDEX TO EXHIBITS

Exhibit 5.1

HALE AND DORR LETTERHEAD

Hybridon, Inc.
345 Vassar Street
Cambridge, Massachusetts, 02139

     Re:   1995 Director Stock Option Plan

Ladies and Gentlemen:

     We have assisted in the preparation of a Registration Statement on Form S-8 (the “Registration Statement”) to be filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”), relating to an aggregate of 400,000 shares of common stock, $0.001 par value per share (the “Shares”), of Hybridon, Inc., a Delaware corporation (the “Company”), issuable under the Company’s 1995 Director Stock Option Plan (the “Plan”).

     We have examined the Certificate of Incorporation and By-Laws of the Company, each as amended and restated to date, and originals, or copies certified to our satisfaction, of all pertinent records of the meetings of the directors and stockholders of the Company, the Registration Statement and such other documents relating to the Company as we have deemed material for the purposes of this opinion.

     In our examination of the foregoing documents, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified, photostatic or other copies, the authenticity of the originals of any such documents and the legal competence of all signatories to such documents.

     We assume that the appropriate action will be taken, prior to the offer and sale of the Shares in accordance with the Plan, to register and qualify the Shares for sale under all applicable state securities or “blue sky” laws.

     We express no opinion herein as to the laws of any state or jurisdiction other than the state laws of the Commonwealth of Massachusetts, the General Corporation Law of the State of Delaware and the federal laws of the United States of America.

Hybridon, Inc.
May 28, 2004
Page 2

     It is understood that this opinion is to be used only in connection with the offer and sale of the Shares while the Registration Statement is in effect.

     Please note that we are opining only as to the matters expressly set forth herein, and no opinion should be inferred as to any other matters.

     Based on the foregoing, we are of the opinion that the Shares have been duly authorized for issuance and, when the Shares are issued and paid for in accordance with the terms and conditions of the Plan, the Shares will be validly issued, fully paid and nonassessable.

     We hereby consent to the filing of this opinion with the Commission in connection with the Registration Statement in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Securities Act. In giving such consent, we do not hereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission.

Exhibit 23.2

Consent of Independent Auditors

     We consent to the incorporation by reference in the Registration Statement (Form S-8) pertaining to the 1995 Director Stock Option Plan of our report dated January 24, 2004 (except for Note 18, as to which date is February 2, 2004), with respect to the consolidated financial statements of Hybridon, Inc. included in its Annual Report (Form 10-K) for the year ended December 31, 2003, filed with the Securities and Exchange Commission.