The effect of contraceptive drugs as inducing agents with accurate quantities of estrogenic hormone on weaned Wistar rats sexual precocity were studied.The results showed that there are much changes in false sexual precocity of weaned rats such as body weight, mammary gland, vaginal orifice, epithelial cells of vagina, ovaries and uterus, which are similar to those of the human beings.Ho wever, there are no different in adrenal, pituitary and thyroid gland in both two groups.