Ten cases of endometrial carcinoma in young women aged 15 to 25 years are presented. Seven of these ten patients exhibited the clinical characteristics of Stein-Leventhal syndrome; of these, three had evidence of polycystic ovaries. Nine of the tumors were well-differentiated, adenoacanthomas (six) or adenocarcinomas (three) and limited to the endometrium. In one case, a moderately differentiated adenosquamous carcinoma involved an ovary and the pelvic wall. Treatment consisted of curettage and progestogens in three patients, one of whom later bore two children. The remainder of the women were treated with abdominal hysterectomy and bilateral salpingo-oophorectomy and/or radiation therapy. All patients for whom follow-up data are available are alive and well without evidence of disease. It is concluded that in selected young patients with well-differentiated endometrial carcinoma limited to the endometrium, conservative hormonal therapy and curettage may be adequate treatment and may preserve fertility.