A malignant ovarian tumour has been diagnosed in 373 patients referred to the R.R.T.I. from January 1966 to Jun 1972. Serious ovarian carcinoma was the commonest type and occurred in 254 patients. The results in these patients are studied in detail after staging according to F.I.G.O. recommendations. Following surgery and postoperative radiotherapy, chemotherapy was started immediately in all patients with progressive disease and after randomization also in 50 per cent of the others. The three-year survival rate in Stage II patients tended to be more favourable following irridation ofthe pelvis and lumboaortic nodes (55 per cent ) than following radiotherapy restricted to the pelvic area (40 per cent). The dose should be 5-6 krad. The five-year survival was 68 per cent for Stage I, 26 per cent for Stage II and nearly zero for Stages III and IV, as well as for patients referred for treatment of a recurrence. In spite of whole-abdomen irradiation 50 per cent of the patients in the latter three groups were deceased within eight months; therefore chemotherapy should be preferred. The main problem in ovarian cancer is late diagnosis. Evaluation of results is difficult because numerous variable factors concerning pathology and treatment make it necessary to sub-divide the patients into groups too small for statistically reliable conclusions. Each treatment factor should be studied by a group of hospitals.