This study analyzes the clinical and pathological features of 76 patients who were diagnosed as having ovarian low malignant potential tumor over a 20-year period: 39 (51.3%) of the tumors were mucinous, 29 (38.2%) serous, three (3.9%) endometrioid, and five (6.6%) mixed. Patients with serous tumors were significantly younger (mean age 40 years) than those with mucinous tumors (mean age 50.5 years). Serous tumors were more frequently bilateral (48.3%) than mucinous tumors (12.8%). The extent of tumor (FIGO stage) at the primary laparotomy was related to the prognosis: the survival of 14 patients with stage III and six patients with stage II tumor was significantly inferior to that of the 56 patients with stage I tumors (P less than .01). Patients with stage III mucinous low malignant potential tumors and pseudomyxoma peritoneii fared badly. Four patients with stage II and 13 patients with stage III tumors had residual tumor after primary surgery. Five of these patients received no subsequent treatment of whom four are alive and well from 5.5 to 19 years after diagnosis. Three patients received pelvic radiotherapy. Eleven patients were treated with chemotherapy for residual or recurrent tumor but only one (9.1%) had an unequivocal response.