Extragonadal germ cell tumors are classified according to the staging system of the International Germ Cell Cancer Collaborative Group (IGCCCG). The 5-year overall and disease-free survival rates for poor prognosis patients are 41 and 48%, respectively after standard-dose chemotherapy. We report the experience of the EBMT Solid Tumours Working Party (STWP) with first-line HDCT with hematopoietic progenitor cell support (HPCS) in patients with poor prognosis extragonadal nonseminomatous germ cell tumor (NSGCT). Between 1990 and 2001, 22 extragonadal NSGCT patients (21 M, 1 F), median age 30 years (range 17-52) were treated with first-line HDCT with HPCS. Primary site was mediastinum in 11 patients, retroperitoneum in 10, and unknown in one. The Carbopec regimen, consisting of high doses of carboplatin, etoposide, and cyclophosphamide, was used in most cases (12 patients). No treatment-related deaths occurred. No patient developed myelodysplasia or a secondary leukemia. In total, 17 of 22 patients (77%) achieved complete remission. At a median follow-up of 50 months (range 26-132), 15 patients (68%) are alive disease-free. The survival rates of patients with poor prognosis extragonadal NSGCT treated with first-line HDCT in the EBMT STWP experience appear higher than that expected according to the IGCCCG classification.