PURPOSE: Patients with completely resected stage IIIA (N2) non-small-cell lung cancer (NSCLC) are at substantial risk for locoregional and systemic recurrence. Adjuvant chemotherapy has recently improved overall control for these patients. We added adjuvant chemotherapy to control presumed micrometastatic disease and then randomized patients to receive radiation therapy (RT) or observation to determine the benefit of local radiation consolidation. PATIENTS AND METHODS: Patient eligibility required histologically documented stage IIIA (radiographically occult N2) NSCLC that was completely resected, with no known residual disease, surgical staging per protocol requirements, Cancer and Leukemia Group B performance status of 0/1, no previous chemotherapy or RT, and minimal laboratory values. All eligible patients received 4 cycles of paclitaxel 200 mg/m2 over 3 hours with carboplatin at an area under the curve of 6 on days 1, 22, 43, and 64 beginning 4-8 weeks after surgery. Two to 4 weeks after chemotherapy, patients were randomized to receive RT as 5000 cGy in 25 fractions over 5 weeks or observation. RESULTS: The study closed after 2 years because of slow accrual. Forty-four patients entered the study; 2 were ineligible, and 5 were not randomized because of progression, adverse reaction, or patient withdrawal. Thirty-seven patients were the basis of this analysis. Median failure-free survival was 16.8 months on the observation arm and 33.7 months on the RT arm, with a 1-year survival rate of 72% on the observation arm and 74% on the RT arm. There were no statistical differences between the observation and RT arms for failure-free survival or overall survival. CONCLUSION: In this small study, consolidation RT after complete resection and adjuvant chemotherapy in stage IIIA NSCLC did not significantly Improve outcome for this high-risk population.