1
                                                                  EXHIBIT 99.1



HYBRIDON                                        NEW RELEASE


                                                          
                                  Hybridon, Inc.                Tel:  617-528-7000    Fax:  617-528-7001
FOR IMMEDIATE RELEASE             620 Memorial Drive            www.hybridon.com
                                  Cambridge, MA 02139     
                                                                CONTACT:  DOUGLAS J. JENSEN
                                                                Vice President, Administration and
                                                                Corporate Development
                                                                617-528-7523




                  HYBRIDON ANNOUNCES SCHEDULED DELISTING FROM
                           THE NASDAQ NATIONAL MARKET

Cambridge, Mass. - September 19, 1997 - Hybridon, Inc. (Nasdaq: HYBN) today
announced that it has been advised by the Nasdaq Stock Market, Inc. ("NASDAQ")
that because the Company was not in compliance with the continued listing
requirements of The Nasdaq National Market. NASDAQ has determined that the
Company is no longer eligible for continued listing on The Nasdaq National
Market. The Company's securities are currently scheduled to be delisted from
The Nasdaq Stock Market effective with the close of business on September 25,
1997. 

The Company intends to appeal the decision to NASDAQ's appeal panel and to
request a delay in delisting until final resolution by the appeal panel. In
addition, NASDAQ has recently adopted new continued listing requirements and
the Company is currently exploring methods for complying with one of the new
requirements. 

If the Company's appeal is unsuccessful and the Company's Common Stock is
delisted from The Nasdaq National Market, the Company intends to make
application for listing on the Nasdaq Small Cap Market. The delisting of the
Company's Common Stock from The Nasdaq National Market may adversely affect the
liquidity of the Company's Common Stock and the ability of the Company to raise
capital. 

Hybridon, headquartered in Cambridge, Massachusetts, is a leader in the
discovery and development of novel medicines for the treatment of important
diseases, based primarily on antisense technology. Antisense technology
involves the use of synthetic segments of DNA and RNA to stop the production of
disease-associated proteins by interacting at the genetic level with target
strands of messenger RNA.



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                    LEADERSHIP IN GENETIC ANTISENSE MEDICINE