Ovarian cancer may be treated with radiation therapy, surgery, chemotherapy, or a combination. To evaluate the contribution of radiation therapy to patient management the cure rate must be estimated; data are presented suggesting that the 5-year survival rate provides a reasonable estimate of the cure rate. Multiple prognostic factors have been shown to affect outcome. A study of patients treated since 1971 showed that stage and postoperative residuum could be used to divide patients into two subgroups, a "poor prognosis" group and a "good prognosis" group; a multifactorial grouping of patients in the good prognosis group who were treated postoperatively with radiation therapy only was further able to divide patients into low-risk, intermediate-risk, and high-risk groups. Studies of radiation therapy for different subgroups are discussed; abdominopelvic irradiation has been shown to improve survival for approximately one-third of patients with cancer of the ovary.