Forty-nine patients with assumed extragonadal germ-cell tumors (retroperitoneum: 39, mediastinum: 8, CNS: 2) were included in the present study. The patients were treated with 'high' (40 mg cisplatin/m2 and 200 mg etoposide/m2 daily x 5) or 'conventional' (20 mg cisplatin/m2 and 100 mg etoposide/m2 daily x 5) doses of cisplatin and etoposide together with bleomycin, depending on the presence or absence of poor prognosis factors. Forty-six patients were evaluable for response and 3 patients were classified as non-responders (1 early death, 2 toxic deaths). Eighty percent obtained complete remission and 76% are alive without evidence of disease after a median observation time of 41 months (88% of patients with primary tumor in the mediastinum, 72% with tumor in the retroperitoneal area, 87% of patients with seminoma and 71% with non-seminoma, respectively). In 48 patients testicular biopsies were performed. In 42% of patients with primary retroperitoneal tumors, carcinoma in situ testis (CIS) was diagnosed. None of the patients with tumors in mediastinum or CNS had CIS in the testicles. The therapeutic outcome for patients with extragonadal germ-cell tumors is now similar to that of patients with very advanced testicular cancer when considered in relation to the presence of prognostic factors. The coexistence of CIS and retroperitoneal tumor could indicate that these tumors are not truly extragonadal or that these lesions have a common malignant progenitor.