Albendazole (Smith Kline, Beecham) in a dose of 20 mg/kg/day was given to B6C3F1 mice exposed to 300 larvae of T. pseudospiralis or T. spiralis. The drug was introduced on days 2, 3 and 4; or 4, 5 and 6; or 18, 19 and 20 after infection. It limited the intensity of intestinal and muscle phases of trichinellosis. Given at the stage of maturation of adult forms and production of new-born larvae, the drug caused almost total elimination of both species from the intestines of mice and a decrease in the numbers of muscle larvae, with a tendency towards a greater reduction of larvae and adults of T. pseudospiralis. The drug did not change the course of infection when given at the phase of infectivity of larvae.