Background: Cisplatin-containing regimens represent the gold standard in the treatment of advanced non-small cell lung cancer, but carboplatin is often preferred for its better toxic profile when palliation is the aim of the treatment. The synergistic effect and tolerability of carboplatin-gemcitabine combination are well known. In this phase 11 trial, we evaluated the activity and safety of a schedule with carboplatin and gemcitabine, defined in our previous phase I trial. Methods: Thirty-seven patients with measurable stage IV nonsmall cell lung cancer were treated with carboplatin, AUC 4.5 mg/ml/min on day 1, and gemcitabine, 800 mg/m(2) on days 1 and 8, every 21 days. All patients were treated until disease progression or intractable toxicity and were evaluated before each course of chemotherapy for toxicity and after every 3 courses for response. Results: After a median follow-up of over 10 months, complete response, partial response, and stabilization of the disease were observed in 3 (8.1%), 9 (24.3%), and 15 patients (40.5%), respectively. Median time to progression was 7 months. At this writing, 27 patients have died, with a median survival of 10 months, and 29 (78.3%),16 (43.2%), and 11 (29.7%) patients are alive after 6,12, and 15 months of follow-up, respectively. Toxicity was mild, and mainly hematological, with a significant correlation with the number of courses of chemotherapy (P = 0.0003). Conclusions: Our results are comparable with those reported in the literature and confirm the good activity and tolerability of the carboplatin-gemcitabine combination. Up to 4 courses of chemotherapy with carboplatin and gemcitabine may represent an interesting option in the palliative treatment of nonsmall cell lung cancer.