A phase II study in patients with stage IIIB/IV non-small cell lung cancer (NSCLC) was carried out to evaluate the clinical activity and toxicity of the chemotherapeutic combination of gemcitabine+vinorelbine (GEM/VNR). Forty-five patients (40 male, 5 female) with a median age of 67 years (range 37-73) and a median ECOG performance status of 1 (range 0-2) were enrolled into the trial. Twenty patients had stage IIIB (two positive supraclavicular nodes and 20 cytologically positive pleural effusion), and 25 had stage IV NSCLC. GEM 1000 mg/m(2) diluted in 250 cc(3) of normal saline was administered iv on days 1, 8, and 15, while VNR was given 30 mg/m(2) on days 1 and 8 every 4 weeks. The median number of courses/patient was 4 (range 3-7). According to an intent-to-treat analysis 2 (4%) patients had a complete response and 16 (36%; 95% CL 22-52%) had a partial response for an overall response rate of 40% (95% CL 26-56%). Twelve (27%) patients had stable disease and 15 (33%) were considered as treatment failures. Median overall survival of the whole series was 8+ months with 33% of patients alive at 1 year. Toxicity was generally mild. WHO grade 3-4 neutropenia was recorded in 22% of cases, grade 1-3 liver toxicity in 6% of patients and neutropenia-unrelated fever in 9%. This multicentre phase II study suggests that the GEM/VNR combination regimen is an active and well tolerated regimen in patients with stage IIIB/IV NSCLC. Larger studies comparing cisplatin-based regimens to new schedules without cisplatin are warranted.