The seed powder of Abrus precatorius L. has traditionally been used as oral contraceptive agent by the women in some rural areas in Bangladesh. The present study aimed to examine the antifertility activity of A. precatorius seed extracts in experimental female rats. Finely ground seeds were extracted with aqueous acetone followed by successive partitioning with n-hexane, ethyl acetate (EtOAc), methanol (MeOH) and water. Water suspended crude seed powder, organic fractions of acetone extract and a standard contraceptive drug ($Nordette^{(R)}28$) were separately administered orally to the female rats for 30 days. n-Hexane, EtOAc and MeOH solubles at the doses of 2, 4 and 6 mg/rat/day, respectively and crude seed powder at 100 mg/rat/day exhibited 100% antifertility activity with lowest levels of serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and $17{eta}$-estradiol. Histological study of ovary and uterus of these rats exhibited reduced number of developing follicles and increased number of atretic follicles in the ovary, and fewer uterine glands with shrunken morphology, reduced endometrial height, poor vascularity and compact stroma in uterus. However, the activities of serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase and the body weight of the rats remained almost unaffected in all the seed extract treated rats compared to control. These results suggest that A. precatorius seed extracts reduced the levels of serum FSH, LH and $17{eta}$-estradiol probably by affecting hypothalamic-pituitary-gonadal axis. The reduced levels of these hormones might have affected the oestrous cycle, follicular development, and subsequently the establishment of pregnancy in treated rats.