The German society of Pediatric Oncology (GPO) designed in 1982 a cooperative study to improve the outlook of patients with malignant testicular germ cell tumors (MAHO 82). So far the combined modality therapy was effective to increase the relapse free survival (Haas et al. 1988). From the data the MAHO 88 protocoll was outlined as follows: Yolk sac tumor: Unilateral orchiectomy; Stage I A - wait and see. Stage I B/C-IV 4 courses standard chemotherapy. If alpha-feto-protein after 2 courses is still positive explorative laparatomy has to be performed. Malignant teratoma (MTI, MTU, MTT), seminoma: Unilateral orchiectomy. Stage I: 4 courses standard chemotherapy. Stage II-IV: 2 courses standard chemotherapy, explorative laparatomy. During explorative laparatomy 3 different approaches are recommended: Modified lymphadenectomy, radical lymphadenectomy or removal of "bulky disease". In case of presence of vital tumor cells patients with teratoma receive "salvage therapy", patients with seminoma receive instead x-irradiation. If only differentiated teratoma cells are found in addition 2 courses of standard chemotherapy are administered. Standard chemotherapy consists of Vinblastine, Bleomycine and Cis-platinum, salvage therapy of VP 16, Ifosfamide and Cis-platinum.