Whether the Russian praziquantel analog azinox can be widely used in the foci of opisthorchiasis was first assessed. The outpatient treatment of 7405 patients with the agent in doses of 30, 40, 60 mg/kg body weight revealed that azinox tolerance did not depend upon the intensity and degree of clinical infection signs but it was slightly worse when a dose of 60 mg/kg was given. Children virtually showed no adverse reactions, in adults their frequency was no more than 52 +/- 1.4%. The parasitological efficiency of azinox in the used doses was 96-99% in children and 82-86% in adults. There was a clinical improvement in 65% of the treated. Thus, the national drug azinox is not inferior to the imported agent bilthricide in tolerance, parasitological and clinical efficiency. Bearing in mind the equal efficiency, but the better tolerance and less cost of the drug doses of 30 and 40 mg/kg body weight, it is advisable to use them in the foci for outpatient treatment.