Abstract： Objective To study the effect of follicle stimulating hormone(FSH)on the secretion of anti-mullerian hormone(AMH)in granulosa cells in patients with polycystic ovarian syndrome(PCOS).Methods From Aug.2008 to Dec.2009,33 patients with PCOS in Reproductive Medicine Research Center,Sixth Affiliated Hospital of Sun Yat-sen University were collected from 8-10 mm antral follicles and classified into the following three groups: FSH-unstimulated granulosa cells(unstimulated group,n =12),exogenous FSH-stimulated granulosa cells(exo-stimulated group,n =12)and internal FSH-stimulated granulosa cells(int-stimulated group,n =21).ELISA and real-time PCR were relatively used to measure protein and mRNA level of AMH.Luciferase reporting vector was constructed to detect the promoter activity of AMH.Results The levels of AMH secretion in PCOS granulosa cells were(11.4 ± 4.0)μg/L in unstimulated group,(7.9 ± 1.1)μg/L in exo-stimulated group and(5.6 ± 1.7)μg/L in int-stimulated group.Both the external and internal stimulation of FSH may suppress AMH secretion significantly(P ＜0.05).The mRNA level of AMH in PCOS granulosa cells were 2.5 ± 1.2 in unstimulated group,which were higher than 1.5 ± 0.5 in exo-stimulated group and 1.1 ± 0.7 in int-stimulated group significantly(P ＜0.05).The luciferase activity of AMH in PCOS granulosa cells were 11.5 ± 2.3 in unstimulated group,8.7 ± 2.4 in exo-stimulated group and 6.8 ± 2.4 in int-stimulated group.The luciferase activity of AMH in unstimulated group was significantly higher than those in exo-stimulated and int-stimulated groups(P ＜0.05).Conclusion FSH may inhibit the excessive secretion of AMH and stimulate follicle growth in PCOS granulosa cells by suppressing activity and expression of promoter.