Four plant extracts i.e. alcoholic extract of Momordica Charantia fruit, both large and small varieties, volatile oil of Ocimum basilicum and of Ocimum sanctum were tested for their antispermatogenic effects in mice and rats. The extracts were given to each group of animals daily in various doses for either 15 or 60 days. A prominent antispermatogenic effect of oil of O. basilicum was observed at the does level of 291.3, 320 and 582.6 mg/kg/day given continuously for both 15 and 60 days. They caused significant reduction in total sperm concentration and in weight of cauda epididymis and other accessory sex organs i.e. seminal vesicle & prostate gland. Water retention seemed apparent in the testis of some animals studied. Histological study showed a disruption of spermatogenesis; lumen of seminiferous tubules were devoid of spermatid and spermatozoa. Other plant extracts did not show any prominent antispermatogenic effects. The plant studied for antifertility effect showed no estrogenicity. Other plant extract which were studied for estrogenicity alone were volatile oil of Alpinia galangal, Cymbopogon citratus, Citrus hystrix, Zingiber cassumunar and Piper betel and also alcoholic extract of Vigna sesquipedalis, Cymbopogon citratus and Gastrochilus panduratus and none of them showed distinct estrogenic activity except for volatile oil of Piper betel and alcoholic extract of Vigna sesquipedalis which contained small amount of estrogenic substances.