In a prospective randomized trial, consolidation treatment with radiotherapy or chemotherapy was compared with no treatment in a series of 172 patients with epithelial ovarian carcinoma, FIGO stage III, with complete surgical remission after primary cytoreductive surgery and induction chemotherapy. In the subgroup with complete surgical and pathologic remission, progression-free survival was significantly (P = 0.032) better in the radiotherapy group (56% at 5 years) than in the chemotherapy group (36% at 5 years) and the untreated control group (35% at 5 years). Overall survival was also most favorable in the radiotherapy group (69% at 5 years). The number of recurrences was lowest in the radiotherapy group. In the subgroup with microscopic residual carcinoma there were no significant differences in survival between the radiotherapy and the chemotherapy-treated patients. Early and late radiation reactions were recorded. Treatment-related side effects were seen most frequently in the radiotherapy group. Late intestinal radiation reactions of a severe type were recorded in 10%.