Objective To investigate the roles of luteinizing hormone releasing hormone (LHRH), follicle stimulating hormone (FSH), human chorionic gonadotropin (hCG) and ovary steroids in regulation of human endometrial stroma cell (ESC) decidualization Methods Stroma cells derived from human endometrium during the proliferative phase were cultured in vitro and treated with physiological doses of estradiol (E 2), testosterone (T),progesterone(P) or LHRH, FSH and hCG Their morphologic changes and prolactin (PRL) production in the media were examined and compared Results Addition of E 2 or T or P stimulated ESC proliferation, resulting in increase of the saturation density The fibroblast morphologic changes to polygonal shape and began to express PRL simutaneously after treatment of P or T P in presence of E 2 or T significantly enhanced PRL production( P