A new schedule with cisplatin and gemcitabine administered biweekly was prospectively evaluated in stage IIIB or IV non-small cell lung cancer. We report the interim analysis of the safety and efficacy with the first 23 patients included. The mean age was 60. Thirteen patients (56.5%) were stage IIIB and 10 (43.5%) were stage IV The overall response rate was 47.8%: 69.2% for stage IIIB and 20% for stage IV The median survival among the 23 patients was 33 weeks and 1-year survival was 39%: 53.8% for stage IIIB and 20% for stage IV Seventy-seven cycles (154 administrations) were given. The mean number of cycles/patient was 3.3 (range: 1 to 6). Of the 154 administrations, 26 were delayed 1 week for recovery from toxicity. The dose intensity (Hryniuk criteria) was 94% of the planned dose. There was one toxic death with grade 4 thrombocytopenia and grade 4 esophagitis. In two patients, grade 3-4 vascular toxicity was observed, with distal arterial ischemic changes in the lower extremities. There were three (3.9%) episodes of grade 2 neutropenia, one (1.7%) of grade 3 and another one of grade 4. No cases of febrile neutropenia were seen. Predominant nonhematologic toxicities were asthenia and nausea/vomiting. This schedule of cisplatin and gemcitabine has a good therapeutic index and, as it is active, enrollment is ongoing to complete the second part of the study.