The authors evaluate the combination of three drugs, vinorelbine, ifosfamide, and cisplatin, which have been shown to produce good response rates and a significant gain in survival when any two of them are given together. Seventy-seven untreated patients with inoperable stage III-IV non-small-cell lung cancer from three centers were included. The combination consisted of cisplatin 30 mg/m2 daily, ifosfamide 1,500 mg/m2 daily, mesna 1,500 mg/m2 daily on days 1-3, and vinorelbine 25 mg/m2 daily on days 1 and 8. Four cycles were administered every 4 weeks for a total of 267 cycles, before an assessment for toxicity, effective dose intensity, response rate, and survival was made. Toxicity was mainly hematologic (grade 3-4 neutropenia (15.7%), anemia (8.2%), and thrombopenia (2.6%)) but did not require granulocyte colony-stimulating factors. Objective response rate was 41.1% (95% confidence interval, 29.5-52.9%) in 68 patients suitable for assessment. The mean time to progression and median survival were 7.7 +/- 1.3 months and 11.6 months, respectively. One-year survival was 47.1%. The effective dose intensity of cisplatin and ifosfamide correlated strongly with survival, whereas stage and performance status did not. This study confirms previously reported favorable results for response and survival rates obtained in stage III-IV non-small-cell lung cancer with the vinorelbine, ifosfamide, and cisplatin combination. Respect of a scheduled dose intensity has a clear-cut influence on survival and should be evaluated routinely in future polychemotherapy trials.