We analyzed the efficacy of radiation therapy and retroperitoneal lymphadenectomy preceded and followed by radiation therapy as curative treatment in 113 patients with clinical stages I and II nonseminomatous germ cell tumors of the testis. Radiation therapy alone was curative in 86 and 82 per cent of the patients with clinical stages I and II disease, respectively, and radiation therapy before and after retroperitoneal lymphadenectomy was curative in 89 and 73 per cent of patients with clinical stages I and II disease, respectively. Of 26 patients with clinical stage II disease in the group receiving radiation therapy before and after retroperitoneal lymphadenectomy only 13 (50 per cent) had pathologic documentation of retroperitoneal metastasis or histologic evidence of nodal metastases that had been destroyed by radiation therapy alone. When analyzed by pathologic stage radiation therapy before and after retroperitoneal lymphadenectomy was curative in 91 and 51 per cent of patients with stage I and II disease, respectively. In our series clinical overstaging may have been responsible for the favorable results of radiation therapy alone, and radiation before and after retroperitoneal lymphadenectomy in the treatment of clinical stage II nonseminomatous germ cell tumors.