Human menopausal gonadotropin (hMG) with different ratios of FSH to LH content (FSH: LH = 1.2:1 (GNR 1.2), FSH:LH = 1.6:1 (GNR 1.6), FSH:LH = 3:1 (GNR 3) in biological activity, respectively) was used in this study to examine the effects of these hMGs on ovary, and subsequent follicular maturation and ovulation. In 5 women, 300 IU of hMG (GNR 1.2, GNR 1.6 and GNR 3) was injected in turns during different midfollicular phases of the cycle (day 5-day 9) and serum estradiol (E2) was measured at 0, 24 hrs, 48 hrs, 72 hrs after injection to assess ovarian response to different hMG. Serum E2 response at 24 hrs, 48 hrs, 72 hrs after injection of hMG compared to the preinjected E2 level were 2.2, 1.8, and 1.5 fold with GNR 1.2; 2.6, 2.4 and 1.9 fold with GNR 1.6; and 2.2, 2.4 and 2.3 fold with GNR 3, respectively. These hMGs were administered in turns to women who were suffering from amenorrhea (6 cases), anovulatory (8 cases) and luteal phase dysfunction (10 cases) for treatment of ovarian dysfunction. The mean doses of hMG per cycle required to induce ovulation were 1,125 IU with GNR 1.2, 1,050 IU with GNR 1.6 and 925 IU with GNR 3 in these 24 women. The success rates for ovulation with GNR 1.2, GNR 1.6 and GNR 3 were 70.8, 79.2 and 87.5%. The appearance rates for ovarian hyperstimulation syndrome (OHSS) with GNR 1.2, GNR 1.6, and GNR 3 were 4.2, 8.3 and 8.3%, respectively. These results infer that a different ratio of FSH to LH in hMG has an effect on follicular maturation and ovulation, and that the increase in the rate of ovulation and prevention of OHSS may accompany the regulating of this ratio, and that hMG with a higher FSH content (ratio of FSH to LH is more than three) should be studied further as a promising agent to use in inducing ovulation in women.