Between 1976 and 1988, 31 patients with mediastinal nonseminomatous germ cell tumors (MNGCT) received initial cisplatin-based chemotherapy of uniform intensity. Eighteen of these patients (58%) obtained disease-free status; 11 with chemotherapy alone and seven with adjunctive surgery. Eleven have remained continuously free of disease. Two have had recurrence of teratoma and are disease-free after resection of teratoma at 12+ and 68+ months. Three patients developed recurrence of germ cell tumor. Three patients developed a hematologic malignancy. Of the 18 patients who obtained disease-free status, 15 remain alive and disease-free. Overall, 13 of the 31 patients and 24 other patients received salvage chemotherapy at Indiana University, Indianapolis, Indiana. Of these 37 patients, six obtained a disease-free status and four (11%) remain alive at 13+, 56+, 78+, and 122+ months, respectively. This series represents the largest series of patients with MNGCT ever reported. Analysis of these data and results from other recent series suggest that approximately 50% of patients with MNGCT will be cured with modern, intense cisplatin-based chemotherapy coupled with adjunctive surgery if needed.