The records of 31 women with ovarian tumors of low malignant potential were retrospectively reviewed to identify factors that determine the prognosis. Median follow-up was 51 months. Eighteen women had stage I disease. Twenty- three women (74%) had serous tumors, of which 46% were bilateral. Nine patients (29%) had concomitant endometriosis or endosalpingiosis. Two patients died of disease; both had mucinous tumors with extraovarian metastases at initial operation and inadequate pathologic sampling of their tumors. These results were combined with those of 970 women identified in previous reports to show that the rate of recurrence or persistence of ovarian tumors rises from 2% for women with stage I disease to 14% for those with stage III or IV disease, while mortality rises from 2 to 5%. Careful staging and pathologic sampling are important for establishing the prognosis. Testing of adjuvant therapy should be limited to patients with extraovarian disease.