In 1935, Stein and Leventhal first described a syndrome consisting of amenorrhea, infertility and a pathologic feature of bilateral polycystic ovaries. Though a number of possible theories regarding etiologic factors have been explored and discussed, the pathologenic mechanisms are including hypothalamus-pituitary axis, ovarian steroidogenesis and adrenal factors. Frequently, this syndrome was associated with endometrial carcinoma or atypical endometrial hyperplasia, Jackson reported 16 cases (37.2%) of association out of 43 patients of Stein-Leventhal syndrome. A case of Stein-Leventhal syndrome associated with endometrial adenocarcinoma was presented. She was a 30-year-old woman with infertility for 5 years and irregular uterine bleeding for 18 days. She was obese and hirsute, but her clitoris was not enlarged. She generally showed secondary female sex characteristics except hirsutism. A diagnostic endometrial curettage showed grade I endometrial adenocarcinoma. Total hystrectomy with bilateal adenexectomy was done. Ovaries were symmetrically enlarged and disclosed capsular thickening and multiple subcapsular cystic follicles. Numerous primordial follicles were noted without any corpus luteum and albicans. The endometrial cavity showed a dark brown ill defined area in the right fundus, and was confirmed to be endometrial carcinoma. Literature review on pathogenesis is Stein-Leventhal syndrome and endometrial adenocarcinoma was done.