Gemcitabine, a pyrimidine analog active in non-small cell lung cancer (NSCLC), is widely used with cisplatin. The potential activity of the combination has not been fully assessed: gemcitabine is not used at its maximum tolerated dose (MTD) and cisplatin shows a clearly dose-related toxicity. This trial was designed to assess the MTD and dose-limiting toxicity (DLT) of low-dose cisplatin and increasing gemcitabine dose. Chemotherapy: cisplatin 50 mg/m2on day 1, gemcitabine starting at 1400 mg/m2on days 1 and 8 every 21 days. Subsequent levels were increased by 200 mg/m2. Forty-two patients with metastatic NSCLC were enrolled (37 males; median age 61 years; squamous cell carcinoma 19 patients; performance status 2, in 13 patients; 18 patients had significant weight loss). MTD was found to be 2600 mg/m2because of DLT in three of six patients: two neutropenic fever and one massive bleeding. Overall toxicity was generally mild consisting mainly of neutropenia. Asthenia was the most common non-hematological effect. Overall response rate was 19 out of 41 patients (46.3%) and median survival was 31 weeks. We conclude that the recommended dose for a phase II dose is gemcitabine 2400 mg/m2days 1 and 8 as a 30-min infusion when given with cisplatin 50 mg/m2.