PRINCIPLE The primary function of the ovarian hormone is to prepare the structural component of the female reproductive system for reproduction by maturing the primodial germ cell and providing the hormonal timing for ovulation. Gonadotropin releasing hormones (GnRH) which are required for the maturation of follicles in the ovaries is regulated by a feed back action of oestrogen and progesterone which is secreted by the granulosa cells of the follicles, act on the pituitary to inhibit the release of follicle stimulating hormone (FSH). Previous reports show that extract of Calotropis procera has a significant effect on the reproductive organ of Wister rat. This study shows how ethanoic extract of Calotropis procera antagonize the effect of ovarian steroid hormone based on the principle of inhibition of the feed back mechanism. LABORATORY ANALYSIS 100 rabbit used for this research were grouped into five of (20) based on the dose per body weight, the last group served as the control. The extract was administered at different rate/dose for 10 days, after which Biochemical/Hormonal assay were done. STATISTICAL ANALYSIS The analyses were done between the groups and their respective control. Independent t- test with p<0.05 was considered significant in all cases. CONCLUSION The ethanoic extract of Calotropis procera proved to be Abortificient plant by decreasing of progesterone and causes hormonal imbalance needed for the maturation of follicles in the ovaries by antagonisng the feed back action for such processes.