To compare gemcitabine and cisplatin (GC) with mitomycin, ifosfamide, and cisplatin (MIC) chemotherapy in patients with stage IIIB (limited to T4 for pleural effusion and N3 for supraclavicular lymph nodes) or stage IV non-small-cell lung cancer (NSCLC). The end points were the evaluation of quality of life (QoL), response rates, survival, and toxicity. Three hundred seven patients were randomized to receive either gemcitabine 1,000 mg/m(2) on days 1, 8, and 15 plus cisplatin 100 mg/m(2) on day 2, every 28 days, or mitomycin 6 mg/m(2), ifosfamide 3,000 mg/m(2), and mesna on day 1 plus cisplatin 100 mg/m(2) on day 2, every 28 days. The whole-blood cell count was repeated on day 1 in both arms and weekly in the GC arm before each gemcitabine administration. No major differences in changes in QoL were observed between the two treatment arms. The objective response rate was 38% in the GC arm compared with 26% in the MIC arm (P =.029). The median survival time was 8.6 months in the GC arm and 9.6 months in the MIC arm (P =.877, log-rank test). Grade 3 and 4 thrombocytopenia was significantly worse in the GC arm (64% v 28%, P <.001), whereas grade 3 and 4 alopecia was reported more commonly in the MIC arm (39% v 12%, P <. 001). We report an increased response rate without changes in QoL and a similar overall survival, time to progression, and time to treatment failure for the GC when compared with the MIC regimen in the treatment of advanced NSCLC.