The efficacy of seven more recently developed anthelmintics of the benzimidazolecarbamate group, i. e., parbendazole, mebendazole, fenbendazole, oxibendazole, cambendazole, oxfendazole and albendazole, has been tested in a series of experiments on white mice artifically infected with Trichinella spiralis. Our results disclosed a relationship between their anthelmintic effect and their chemical structure. This finding might be of importance in a targeted synthesis of new, effective, derivates of benzimidazole, e. g., in the therapy of trichinellosis and in the choice of the most effective drug.