The importance of prognostic factors in the individual treatment of patients with disseminated germ cell tumours. Following chemotherapy for disseminated testicular cancer, 55 patients underwent surgery because of residual tumour. The histological findings were viable tumour in 12 patients, mature teratoma in 12 and fibrosis and/or necrosis in 31. Retroperitoneal abdominal masses were evaluated radiographically before and after chemotherapy. The reduction in size of these masses after chemotherapy appeared to have prognostic significance. A decrease of more than 70% was always associated with fibrosis. A residual mass over 50 mm indicated viable tumour or mature teratoma. Seminoma or embryonal carcinoma was more likely to result in fibrosis/necrosis in the resected tissue. Both the Indiana and the EORTC classification models can be used for prognosis. Radiographic measurements before and after chemotherapy are of considerable prognostic significance. These objective indicators help in planning treatment and so diminish the side effects of therapy and maintain or even increase the high cure rate in disseminated testicular cancer. 