High-dose cis-platinum treatment (180 mg/m2 per cycle) in combination with VP16 and bleomycin was given to 14 patients with highly advanced nonseminomatous malignant germ cell tumours (total: 31 cycles). Cis-platinum was administered in infusions of 0.9% NaCl given daily for 3 days with 3-week intervals. An intensive hydration regimen (71 NaCl/day) provided a urinary output of at least 1000 ml/4 h. The response and side effects were evaluated. Ultimately 11 of 12 patients evaluable for treatment effect were rendered tumour-free and are alive with NED. All 14 patients were evaluable for toxicity; 2 developed life-threatening lung edema during the initial prehydration period and did not continue the high-dose cis-platinum schedule. After one to four cycles of high-dose cis-platinum treatment the 131I-Hippuran clearance was reduced by 28%. Decreased kidney function evaluated by 131I-Hippuran clearance was the reason for discontinuation of treatment in 5 patients. Patients with ureteric obstruction represented a high-risk group for reduction of kidney function. High-dose cis-platinum therapy is an intensive treatment demanding a high level of investment of resources, which has promising response rates in patients with highly advanced malignant germ cell tumours. Short-term clinically significant reduction of the kidney function can be avoided by intensive hydration of the patient.