Phase II studies of single agent and CDDP-based two drug combination were performed in 189 patients with inoperable non-small cell lung cancer. Six drug regimens were performed: CDDP alone, VDS alone, Epi-ADM alone, CDDP + VDS, CDDP + CPA, CDDP + ADM. The response rates were 15.4% (6/39) with CDDP alone, 8.0% (2/25) with VDS alone, 6.1% (2/33) with Epi-ADM alone, 26.7% (8/30) with CDDP + VDS, 14.3% (4/28) with CDDP + CPA, 17.6% (6/34) with CDDP + ADM and one CR was performed with CDDP + ADM. In patients with no prior chemotherapy, the response rates were 20.0% (6/30), 11.8% (2/17), 12.5% (2/16), 26.7% (8/30), 16.0% (4/25) and 25.0% (3/12), respectively. The median survival times were 25, 27, 23, 33, 25, and 45 weeks, respectively. The efficacy of CDDP in non-small cell lung cancer patients was re-confirmed, and that of CDDP + VDS, CDDP + ADM was suggested. No death due to toxicity occurred and toxicity was generally tolerable.