In a phase II study 40 patients with non-small-cell lung cancer were treated with 100 mg/m2 cis-diamminedichloroplatinum (II) (DDP) i.v. on day 1, combined with VP 16-213 (VP) in a dose of either 80 mg/m2 daily i.v. on days 1, 2 and 3 or 120 mg/m2 daily by mouth on days 3, 4, 5 and 6. The course was repeated every 3 weeks. In 30 evaluable patients, 10 partial remissions were recorded with a median duration of 3 months. Eleven patients had stable disease and 9 showed progression under treatment. Leukopenia was more pronounced with intravenous administration of VP than with oral VP (median leukocyte nadir 2400/mm3 and 3700/mm3 respectively). Two patients had thrombocytopenia under 50,000/mm3. All patients suffered from moderate to marked nausea and vomiting. All patients had alopecia. Nine patients had serum creatinine elevations over 1.4 mg/dl. Six patients with renal toxicity were treated in one institution with incorrectly applied forced diuresis during DDP administration. DDP and VP are an active regimen for remission induction in non-small-cell lung cancer. Due to cumulative and marked gastrointestinal intolerance this regimen cannot be given over prolonged periods of time.