Serum levels of hCG, AFP, CEA and testosterone were measured in 20 patients with testicular tumors for an evaluation of their clinical significance as tumor markers. HCG was elevated in those with chorional and syncytiotrophoblastic cell tumors, but it was also detected in some cases of embryonal carcinoma and seminoma, suggesting the presence of hCG-producing elements. AFP was exclusively elevated in embryonal and yolk sac tumors. CEA and testosterone were mostly normal in all patients. HCG and AFP fluctuated in good correlation with the clinical course. Thus, hCG and AFP were valuable tumor markers for testicular tumors for the diagnosis of histological type and stage and monitoring the therapeutic effect and prognosis.