The GPOH-MAHO trials designed in 3/82 and 7/88 for treatment of childhood testicular germ cell tumors registered 3/92 105 pts. In MAHO 82 study 57 pts. and in MAHO 88 study 48 pts. were treated. Histologically 60% of the tumors revealed yolk sac tumors (YST), 22% teratomas (TD) and 18% malignant teratomas (MTI, MTU, MTT). Beside unilateral orchiectomy, according to stage and histology a stratified chemotherapy was administered. Standard chemotherapy consisted of 4 courses VLB, BLM, DDP, after 2 courses standard chemotherapy if vital tumor was suspected: explorative laparatomy. According to laparatomy some patients received salvage chemotherapy of 3 courses VP 16, IFO and DDP. The following results were obtained: YST: 59 pts. with stage I. Of these 10 received adjuvant chemotherapy with VLB, BML, DDP. 49 pts. were followed according to wait and see policy and not treated by adjuvant chemotherapy; 8 pts. had a relapse. 5 were treated with standard chemotherapy and 1 pt. with salvage therapy. 1 pt. had stage II and another stage III. Both received standard chemotherapy. The survival of all 61 pts. is 100%. Median observation time is 4 years. TD: 25 pts. had stage I. No chemotherapy was given. The relapse free survival is 100%. Median observation time is 4 years. Malignant teratomas (MTI, MTU, MTT): 8 pts. had stage I. Of these 3 received adjuvant chemotherapy, 5 lymphadenectomy without chemotherapy. All patients survived without relapse. 8 pts. had stage II and received standard chemotherapy, of these 4 pts. had stage IIc and explorative laparotomy was done. According to the result 2 pts. received salvage therapy. All pts. survived relapse free.(ABSTRACT TRUNCATED AT 250 WORDS)