Of 61 patients with stage IA borderline ovarian tumors, 41 were treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy, and 20 were treated by a variety of more limited operations, including cystectomy with (one patient) and without (three patients) a contralateral ovarian wedge biopsy, and unilateral salpingo-oophorectomy with (six patients) and without (ten patients) a contralateral wedge biopsy. In the group treated conservatively, there were 11 serous, seven mucinous, and two mixed seromucinous borderline tumors, whereas in the total abdominal hysterectomy and bilateral salpingo-oophorectomy treatment group there were 26 serious, 12 mucinous, and three mixed seromucinous borderline tumors. After a mean follow-up of 89 months (range 36 to 244 months), subsequent borderline neoplasms had developed in three patients (15%) with serious borderline tumors initially treated conservatively and in two patients (5%) with serous or mixed seromucinous borderline tumors initially treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy. No patient with a mucinous borderline tumor treated either conservatively or with total abdominal hysterectomy and bilateral salpingo-oophorectomy developed a subsequent neoplasm. All 61 patients in the study group are alive and free of disease, including those who developed recurrent neoplasm.