Exhibit 99.1

               HYBRIDON RAISES $14.6 MILLION IN PRIVATE FINANCING

CAMBRIDGE, MASS, SEPT. 2 -- Hybridon, Inc. (OTC Bulletin Board: HYBN.OB - News)
today announced it has raised $14.6 million in gross proceeds from a private
financing with institutional and accredited investors. In the financing, the
Company sold approximately 20 million shares of common stock and warrants to
purchase approximately 6 million shares of common stock. The warrants to
purchase common stock have an exercise price of $1.00 per share and will expire
if not exercised by August 28, 2008. Of the amount raised, approximately 70%
came from U.S. investors and approximately 30% came from non-U.S. investors.
Spencer Trask Ventures, Inc. acted as a selected dealer for Hybridon in the U.S.

The net proceeds to Hybridon, excluding further proceeds from the exercise of
warrants, total approximately $13 million. Hybridon currently intends to use
these funds for ongoing research and product development activities, including
costs of continuing and future clinical trials of its two lead compounds,
HYB2055, a 2nd generation CpG DNA immunomodulatory oligonucleotide, and
GEM(R)231, a 2nd generation antisense compound designed to inhibit protein
kinase A. In addition, funds will be used for further preclinical studies of the
Company's immunomodulatory oligonucleotide (IMO(TM)) compounds and additional
2nd generation antisense agents. Proceeds will also be used for other general
and administrative purposes including the settlement of Hybridon's 9%
convertible subordinated notes, which total $1.3 million in principal.

In connection with the private placement, Hybridon also issued warrants to
selected dealers and placement agents which assisted the Company with the
private placement, including Spencer Trask. These include warrants to purchase
approximately 2.5 million shares of common stock at an exercise price of $0.73
per share and warrants to purchase approximately 1.3 million shares of common
stock at an exercise price of $1.00 per share. These warrants will expire if not
exercised by August 28, 2008.

The securities offered by Hybridon in this private placement have not been
registered under the Securities Act of 1933, as amended, and may not be offered
or sold in the United States absent registration or an applicable exemption from
registration requirements. Hybridon has agreed to file a registration statement
with the Securities and Exchange Commission registering the resale of the shares
of common stock issued in this private placement, the shares of common stock
issuable upon exercise of the warrants issued in this private placement and the
shares of common stock issuable upon exercise of the warrants issued to the
selected dealers and placement agents.

This notice is issued pursuant to Rule 135c under the Securities Act of 1933 and
shall not constitute an offer to sell or the solicitation of an offer to buy,
nor shall there be any sale of these securities in any state in which such
offer, solicitation or sale would be unlawful prior to the registration or
qualification under the securities laws of any such state.



ABOUT HYBRIDON

Hybridon, Inc. is a leader in the discovery and development of novel
therapeutics and diagnostics, based on synthetic DNA. The Company now has four
technology platforms: 1) Synthetic immunomodulatory oligonucleotide (IMO(TM))
motifs that act to modulate responses of the immune system; 2) Antisense
technology which uses synthetic DNA to block the production of disease-causing
proteins at the cellular level; 3) Synthetic DNA drug candidates that enhance
the antitumor activity of certain marketed anticancer drugs, thereby increasing
their effectiveness; and 4) Cyclicon(TM) probes, novel synthetic DNA structures
for identifying gene function, which can be used for target validation and drug
discovery as well as for PCR-based gene amplification.

This press release contains forward-looking statements concerning Hybridon that
involve a number of risks and uncertainties. For this purpose, any statements
contained herein that are not statements of historical fact may be deemed to be
forward-looking statements. Without limiting the foregoing, the words,
"believes," "anticipates," "plans," "expects," "estimates," "intends," "should,"
"could," "will," "may," and similar expressions are intended to identify
forward-looking statements. There are a number of important factors that could
cause Hybridon's actual results to differ materially from those indicated by
such forward-looking statements including risks as to whether results obtained
in preclinical studies or clinical trials will be indicative of results obtained
in future preclinical studies or clinical trials, or warrant further clinical
trials and product development; whether products based on Hybridon's technology
will advance through the clinical trial process and receive approval from the
United States Food and Drug Administration or equivalent foreign regulatory
agencies; whether, if such products receive approval, they will be successfully
distributed and marketed; whether the patent and patent applications owned or
licensed by Hybridon will protect the Company's technology and prevent others
from infringing it; whether Hybridon's cash resources will be sufficient to fund
product development; and such other important factors as are set forth under the
caption "Risk Factors" in Hybridon's Quarterly Report on Form 10-Q for the
quarter ended June 30, 2003, which important factors are incorporated herein by
reference. Hybridon disclaims any intention or obligation to update any
forward-looking statements.