Navelbine (vinorelbine, NVB) is the first semisynthetic 5'-nor-vinca-alkaloid selected for clinical trial. NVB has been shown to have a good level of activity against different experimental solid tumors in animals, with low neurotoxicity. In the phase II study, 78 patients with an inoperable non-small-cell lung cancer (NSCLC) were treated with NVB at a weekly dose of 30 mg/m2. No patient had previously received chemotherapy. Twenty-three of the 78 eligible patients showed a partial response (29.4% with a 95% confidence limits: 19.5-39.5). Eight patients were not evaluable and the percentage of partial response were 32.8% in the evaluable patients group. The median response duration was 34 weeks, and the median survival time for the overall population reached 33 weeks. Grade 3-4 leukopenia was seen in 12.5% of cycles. No thrombocytopenia occurred. At the dosage schedule used, NVB seems a very promising agent in the treatment of NSCLC.