Between January 1975 and January 1987, 80 patients underwent primary surgery at Brigham and Women's Hospital for epithelial ovarian tumors of borderline malignancy. Surgical staging revealed 52 (65%) patients with stage IA, 2 (2.5%) with stage IB, 10 (12.5%) with stage IC, 4 (5%) with stage II, 11 (13.8%) with stage III, and 1 (1.2%) with stage IV. All 37 patients with mucinous tumors had stage I disease, whereas 13 (33%) of 39 patients with serous tumors had stage II-IV disease. The mean sizes of mucinous and serous ovarian tumors were 18.7 and 10 cm, respectively. At initial surgery, 48 (60%) patients had a total abdominal hysterectomy with bilateral salpingo-oophorectomy and 16 (20%) had an oophorectomy. Sixteen (20%) patients underwent cystectomy, 6 (37.5%) of whom subsequently had an oophorectomy. All 10 patients treated by cystectomy alone have remained disease free. CA-125 levels were normal in 5 patients with stage I disease, but were elevated in 6 of 8 patients with more advanced tumors. Current disease status was determined in 72 patients (90%); 69 (95.8%) are alive and disease free, 1 (1.4%) patient is alive with tumor, and 2 (2.8%) patients died, free of disease.