The summarized data on the biological activity of acridoneacetic acid, a low-molecular interferon inducer are presented: the amount and type of induced interferon, producer cells, interaction with viruses; the antiviral, antitumoral and anti-inflammatory activity of the preparation has been demonstrated. The specific features of interferon induction by virus (a biological inducer), in contrast to acridoneacetic acid (a chemical inducer) have been noted. The possible mechanisms of interferon induction by low-molecular interferonogen are considered. A number of interferonogens, salts of acridoneacetic acid, proposed as medicinal preparations are considered. The results of the clinical use of Cycloferon, a medicinal form of acridoneacetic acid, are presented.