Eleven cases of endometrial stromal sarcoma were obtained from the files of Yale New Haven Hospital from 1969 to 1981 for clinicopathologic correlation and determination of the outcome after hormonal therapy with progestational agents. Histologically, nine of the tumors were classified as low grade stromal sarcomas, and two were of a high grade. All of the patients underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy as the main modality of treatment. Two patients received radiation, three adjuvant chemotherapy, two hormonal therapy (Megace 160 mg qd), three received no therapy at all, and the treatment is not known in one case. Two of the patients who received no therapy had recurrences and were placed on hormonal therapy. The remaining patient was a stage IV and died of disease 3 months after diagnosis. All four of the patients who were treated with hormonal therapy are alive, free of disease, or with stable tumor from 2 to 6 years after diagnosis. The presence of estrogen receptors (ER) and progestin receptors (PR) was demonstrated in the tumor in some of the cases; this may explain the sensitivity of this neoplasm to hormonal therapy.