Vinorelbine and gemcitabine are both active as single agents in advanced non-small cell lung cancer (NSCLC). Because of their different mechanisms of action, good tolerability and possible administration on an out-patient basis, vinorelbine/gemcitabine should be an interesting combination for palliative chemotherapy. Thus, we initiated a phase I dose-escalation trial in order to determine the maximum tolerated doses of vinorelbine/gemcitabine that can be administered without haematopoietic growth factors, the dose-limiting toxicities and the most frequent side-effects of this novel combination. 40 chemotherapy-naïve patients with advanced NSCLC were treated with different doses of vinorelbine/gemcitabine on days 1, 8 and 15, and this treatment cycle was repeated on day 29. Vinorelbine and gemcitabine were escalated from 10 to 30 mg/m2 and 600 to 1200 mg/m2, respectively. A total of 63 treatment cycles were administered and 27 patients received at least two treatment cycles. Dose-limiting toxicities were leucopenia plus thrombocytopenia (2 patients) and mucositis (1 patient). The maximum tolerated dose was established at 25 mg/m2 vinorelbine combined with 1200 mg/m2 gemcitabine. Frequent side-effects were leucopenia, anaemia, nausea/vomiting, flu-like symptoms, skin rashes and elevation of liver enzymes. The recommended phase II doses are 20-25 mg/m2 vinorelbine combined with 1000-1200 mg/m2 gemcitabine on days 1, 8 and 15, but myelosuppression will have to be carefully monitored.