Abstract: A 26-year-old unmarried woman with irregular menstruation for 4 years was admitted for an intrauterine space-occupying mass. Pathological examination before surgery showed moderately to poorly differentiated endometrial adenocarcinoma. The patient underwent laparoscopically assisted epifascial panhysterectomy with bilateral salpingo-oophorectomy. Pathological examination of the surgical specimens reported moderately to poorly differentiated endometrial adenocarcinoma and stage II clear cell carcinoma. The patient then received chemotherapy and remained alive without evidence of recurrence. Young women with polycystic ovarian syndrome are at high risk of developing endometrial carcinoma, but concurrent clear cell carcinoma is rare. Careful evaluation before and after treatment are essential to improve the patients’prognosis.