We reviewed 31 cases of endometrial stromal tumors treated on the Gynecology Service at Memorial Sloan-Kettering Cancer Center from 1970 to 1984. Twenty-two patients had endolymphatic stromal myosis and 9 patients had endometrial stromal sarcoma. Twenty-six patients initially had disease confined to the uterus. Following hysterectomy, 7 patients received various adjuvant therapies, but no active adjuvant regimen was identified. All 3 patients who presented with advanced endometrial stromal sarcoma died of rapidly progressive disease; only 2 of 6 patients with stage I endometrial stromal sarcoma developed recurrence. Among patients with endolymphatic stromal myosis, a higher recurrence rate was noted in patients with residual ovarian tissue (100%) than in those without residual ovarian tissue (43%). Fifteen patients were treated for recurrent disease (13 with endolymphatic stromal myosis, 2 with endometrial stromal sarcoma). Following attempts to resect disease surgically, objective responses were attained with both chemotherapy (57%) and radiation (40%). The median survival following treatment of recurrent disease was 46 months. Actuarial survival for all patients in this study was 76% at 5 years and 69% at 10 years.