Patients with no macroscopic residual disease after primary cytoreductive operation are considered to have the most favorable prognosis among subjects with advanced ovarian carcinoma. Nevertheless, approximately half of these patients eventually die of recurrent disease. The identification of more cogent prognostic factors within this subcategory of patients might allow for improved design of postoperative adjuvant treatment. The prognostic significance of several clinical and pathologic factors, including DNA content, was evaluated in 27 patients afforded complete cytoreduction at primary operation who were participants in prospective clinical trials of adjuvant chemotherapy for advanced ovarian carcinoma. After a median follow-up of 120 months, 14 patients were alive without evidence of disease and 13 had died of progressive disease. DNA index provided statistically significant prognostic information on the outcome (P = 0.02). Eleven of the 16 patients with a DNA index more than 1.3 died of tumor (8-year survival, 35%), whereas only 2 of the 11 with a DNA index less than 1.3 died (8-year survival, 79%). In addition, menopausal status was of borderline significance for predicting survival (P = 0.04). The prognostic impact of the DNA index became progressively more evident with longer follow-up. Confirmation of this observation in larger sample populations may provide useful information for designing future clinical trials for this prognostically favorable subset of patients who have optimal reduction with advanced ovarian epithelial carcinoma.