meenakshi Cissampelos pareira Linn. is one of the folk medicinal plants commonly used as antifertility agent in some places of India. The aim of the present study was to evaluate the validity of the antifertility effect of the leaf extract. Cissampelos pareira leaf extract, when administered orally, altered the estrous cycle pattern in female mice, prolonged the length of estrous cycle with significant increase in the duration of diestrus stage and reduced significantly the number of litters in albino mice. The analysis of the principal hormones involved in estrous cycle regulation showed that the plant extract altered gonadotropin release (LH, FSH and prolactin) and estradiol secretion. The results indicated the antifertility effect of Cissampelos pareira leaf extract in female albino mice. The oral LD50 of the extract was found to be 7.3 g/kg in mice.