Objective: To investigate the effects of leptin and neuropeptide Y on steroidogenesis of human ovarian granulosa cells in vitro. Methods: Human ovarian granulosa cells were isolated from follicular fluid obtained during oocyte retrieval of in vitro fertilization-embryo transfer program and cultured for 2 days with various concentration of leptin(1,10,100 ng/ml) or neuropeptide Y (1×10-6, 1×10-7, 1×10-8 mol/L) alone or both,or with the combination of human chorionic gonadotropin (hCG 0, 20 IU/L). The medium was collected for estradiol (E2) and progesterone (P) measurements. Results: (1)Whether hCG existed or not, the adding of leptin did not alter estradiol and progesterone production by human granulosa cells (P>0.05).(2) Only when the concentration of neuropeptide Y was at 1×10-7mol/L,estradiol level was lower than that in the control (P<0.05).(3) The levels of estradiol in neuropeptide Y (1×10-7mol/L) plus hCG group were significantly higher than those with neuropeptide Y alone(P<0.05). (4) In the absence of hCG, the levels of estradiol in neuropeptide Y (1×10-7mol/L)plus leptin (10 ng/ml) group were significantly higher than those with neuropeptide Y(1×10-7mol/L)alone(P<0.05).Conclusions: (1)Leptin alone produced no direct effect on secretion of E2 and P from granulosa cells in vitro.(2)Neuropeptide Y alone may inhibit the secretion of E2, but the inhibition would probably be blocked with the presentation of hCG.(3)Leptin probably blocked the inhibition of neuropeptide Y on E2 secretion, and this may indicate that there were some coordination between leptin and neuropeptid Y on the level of ovarian function. Objective: To investigate the effects of leptin and neuropeptide Y on steroidogenesis of human ovarian granulosa cells in vitro. Methods: Human ovarian granulosa cells were isolated from follicular fluid obtained during oocyte retrieval of in vitro fertilization-embryo transfer program and cultured for 2 days with various concentrations of leptin (1, 10, 100 ng / ml) or neuropeptide Y (1 × 10-6, 1 × 10-7, 1 × 10-8 mol / L) alone or both, or with the combination of human chorionic gonadotropin Results: (1) Whether hCG existed or not, the adding of leptin did not alter estradiol and progesterone production by human granulosa (2) Only when the concentration of neuropeptide Y was at 1 × 10-7 mol / L, estradiol level was lower than that in the control (P <0.05). (3) The levels of estradiol in Neuropeptide Y (1 × 10 -7 mol / L) plus hCG groups were significantly higher than those with neuropeptide Y alone (P <0.05). (4) In the absence of hCG, the levels of estradiol in neuropeptide Y (1 × 10 -7 mol / L) plus leptin (10 ng / ml) group were significantly higher than those with neuropeptide Y -7mol / L) alone (P <0.05) .Conclusions: (1) Leptin alone produced no direct effect on secretion of E2 and P from granulosa cells in vitro. (2) Neuropeptide Y alone may inhibit the secretion of E2, but the inhibition could probably be blocked with the presentation of hCG. (3) Leptin probably blocked the inhibition of neuropeptide Y on E2 secretion, and this may indicate that there were some coordination between leptin and neuropeptid Y on the level of ovarian function.