The present review of selected clinical trials of the use of radiotherapy in ovarian cancer indicates that this modality has a curative role in postoperative treatment. Techniques which encompass the entire peritoneal cavity produce superior survival rates and better control of occult upper abdominal metastasis than the techniques which treat only part of the peritoneum. The volume of residual tumour, its pathology subtype and grade, and the presenting stage each independently influence the outcome of therapy. An approach to planning treatment which considers all of these variables is presented. No long-term survival data exist to permit a comparison of the relative efficacies of abdominopelvic irradiation and cisplatin-based combination chemotherapy regimes, but a rational strategy for choice of treatment can be devised. Combined modality therapy is an important area for future study.