The synthesis of alkyl 5(6)-(benzimidazol-2-ylcarbamoyl)benzimidazole-2-carbamates (6, 7), and alkyl 5(6)-(4-substituted piperazin-1-yl)benzimidazole-2-carbamates (31-40) has been carried out. When the compounds were tested for their anthelmintic activity against Ancylostoma ceylanicum in hamsters, Hymenolepis nana in rats, Litomosoides carinii in cotton rats, and Dipetalonema viteae in Mastomys natalensis, methyl 5(6)-(4-benzoylpiperazin-1-yl)benzimidazole-2-carbamate (31), methyl 5(6)-[4-(2-furoyl)piperazin-1-yl]benzimidazole-2-carbamate and methyl 5(6)-[4-[(diethylamino)carbonyl]piperazin-1-yl]benzimidazole- -2-carbamate (36) showed 100% elimination of tapeworms H. nana at three oral doses of 100-250 mg/kg. Compounds 34 and 36 also killed the microfilariae and adult worms of L. carinii in cotton rats at an intraperitoneal dose of 30 mg/kg given for 5 days.