The design and synthesis of a series of alkyl 5(6)-substituted benzimidazole-2-carbamates (1-13), 7-chloro-4-(4-substituted phenyl)aminoquinolines (14-16), l,2-dim ethyl-3-m ethoxycarbonyl- 4,5-disubstituted pyrroles (17-19) and some compounds belonging to the class pimelonitrile (20), dihydroquinoline (21), pyridine (22), pyridoquinoline (23) and tetrahydropyrimidine (24) have been carried out as possible antifilarial agents. All these compounds have been evaluated for their activity against male and female adult worms of Litomosoides carinii in cotton rats. The effect of these compounds was also observed on the reproductive system (condition of developing microfilariae and their release from uterus) of adult female worms. In this study, three types of compounds were discovered: (a) those which showed activity on both the male and female adult worms and also had sterilizing effects on surviving adult females (1 -3 , 6 - 9 , 13, 19), (b) those which only sterilized the adult females (14-16 , 21, 24), and (c) those which had no effect on female reproduction but killed only adult worms (4, 5, 11, 12, 17,18, 20, 22, 23). This tends to open up a new avenue in the chemotherapy of filariasis and the future scope of work on chemosterilization of adult females has been discussed.