Fenvalerate,a synthetic pyrethroid,is widely used in agriculture and other domestic applications in China.Recently,Fenvalerate has been suspected to be one of the endocrine-disrupting chemicals(EDC).In this study, we investigated the effects of fenvalerate on follicle-stimulating hormone(FSH)-stimulated progesterone (P4) production by human ovarian luteinizing-granulosa cells (hGLCs). After 24 h incubation,fenvalerate inhibited FSH-stimulated P4 production.At the same time, FSH-stimulated cAMP also decreased.Due to calcium and Ca2+-calmodulin (CaM) system involving gonadotropin-stimulated steroidogenesis by granulosa cells,we then evaluated the effects of fenvalerate on trifluoperazine (TFP)-and verapamil-driven FSH-stimulated P4 production.The results showed that calcium or calmodulin might play a role in fenvalerate-induced alterations in FSH-stimulated P4 biosysthesis.Then,the effects of fenvalerate on calcium homeostasis in hGLCs were studied. The result showed that 5μM fenvalerate induced a slow increase in[Ca2+] in hGLCs by using a fluorescent Ca2+ indicator fluo-3/AM. The changes in total concentration of CaM in hGLCs induced by fenvalerate were evaluated by a method of immunofluorescence. There is a significant increase in all treated groups.In summary, fenvalerate could inhibit FSH-stimulated P4 production. Also, fenvalerate interferes with calcium homeostasis in hGLCs. The effects of fenvalerate on FSH-stimulated ovarian steroidogenesis may be mediated partly through calcium signal.