Objective: The West Japan Study Group For Lung Cancer Surgery (WJSG) conducted a randomized controlled trial in order to assess the usefulness of adjuvant chemotherapy for NSCLC. Methods: Patients with completely resected NSCLC (stages I and II) were enrolled in the trial. These patients were randomized into two groups: a surgery alone group; and a chemotherapy group which received intravenous administration of two courses of 4-week PVM chemotherapy (80 mg/m² of Cisplatin on day 1, 2–3 mg/m² of Vindesine on day 1 and/or day 8, and 8 mg/m² of Mitomycin C on day 1), after which they took 400 mg/day of UFT (Uracil+Tegaful) orally for 1 year. Results: Among 229 patients registered for the study from August 1988 to July 1990, 225 were available cases (116 patients in the surgery alone group, and 109 patients in the chemotherapy group). No bias in prognostic factors could be found between the two groups. The 5-year survival rate was 71.1% for the surgery-alone group and 76.8% for the chemotherapy group with no significant difference observed. However, subset analysis demonstrated that PVM therapy improved the post operative survival of pT1N0 patients (the 5-year survival rats: 75.3% for the surgery alone group, and 90.7% for the chemotherapy group P≪0.05). Conclusions: It is interesting to find that among pT1N0 patients, who were not regarded as a target of chemotherapy, those receiving chemotherapy showed significantly better prognostic results. These findings suggest the necessity of further studies on the adjuvant chemotherapy, even in the early stages.