In the course of a preliminary clarification of the mechanisms of the leaf mixture extract of Aloe buettneri, Justicia insularis, Dicliptera verticillata and Hibiscus macranthus, locally used to regulate the menstrual cycle and to treat dysmenorrhea or cases of infertility in women, pieces of proestrus rat ovary were incubated in the presence of increasing concentration of the plant extract and/or human Chorionic Gonadotropin (hCG). The in vitro production of estradiol and progesterone by ovarian cells of proestrus rat was significantly increased in the presence of various concentration of hCG (P < 0.05). The different concentration of the plant extract increased the production of estradiol by twofold. In addition, the in vitro production of estradiol by ovarian cells increased by 13-fold when they were incubated with hCG (0.1 IU/ml) and a concentration of 130 microg/ml of the plant extract. These results clearly attest the direct effects of some chemical components of the leaf mixture of the plants on ovarian steroidogenesis.