Surgical treatment of endometriosis was attempted in 50 female rhesus monkeys (Macaca mulatta). Endometriosis was clinically staged as minimal (8% of the monkeys), moderate (18%), or massive (74%). Elective euthanasia was performed in 15 (30%) of the monkeys. Total abdominal hysterectomy with bilateral salpingo-oophorectomy was performed in 30 (60%) of the monkeys, and bilateral salpingo-oophoretomy alone was performed in 5 (10%) monkeys. Statistical differences were not found in Kaplin-Meier survival curves between the different stages of endometriosis (P = 0.6297).