Gavage administration of cambendazole at 50 mg/kg was found to eliminate a 7 hour Trichinella spiralis infection in mice. Cambendazole was also found to be highly active against the muscle phase of trichinosis. Partial activity was also indicated against migratory larvae and adult worms. Cambendazole appears to have a sterilising effect on adult T. spiralis. It is postulated that cambendazole has potential therapeutic value.