From March 1983 through January 1990, two hundred sixty six patients with non-mall cell lung cancer were treated with external radiation therapy at the Department of Therapeutic Radiology, Kangnam St. Mary's Hospital, Catholic University Medical College. A retrospective analysis was performed on eligible 116 patients who had been treated with radiation dose over 40 Gy and had been able to be followed up. There were 104 men and 12 women. The age ranged form 33 years to 80 years (median; 53 years). Median follow up period was 18.8 months ranging from 2 months to 78 months. According to AJC staging system, there were 18(15.5%) patients in stage II, 79(68.1%) patients in stage III and 19(16.4%) patients in stage IV. The pathologic classification showed 72(62.8%) squamous cell carcinomas, 16(13.8%) unknown histology. In Karnofsky performance status, six(5.2%) patients were in rage below 50, 12(10.4%) patients between 50 and 60, 46(39.6%) patients between 60 and 70, 51(44.0%) patients between 70 and 80 and only one (0.8%) patients was in the range over 80. Sixty (51.7%) patients were treated with radiation therapy (RT) alone. Thirty three (28.4%) patients were treated in combination RT and chemotherapy, twenty three(19.8%) patients were treated with surgery followed by postoperative adjuvant RT, and of 23 patients above, five(4.3%) patients, were treated with postoperative RT and chemotherapy. Overall response according to follow-up chest X-ray and chest CT scans was noted in 92.5% at post RT 3 months. We observed that overall survival rates at 1 year were 38.9% in stage II, 20.8% in stage III, and 11.5% in stage IV, and 2 year overall survival rates were 11.1% in stage II, 20.8% in stage III and 10.5% in stage IV, respectively. We evaluated the performance status, radiation dose, age, type of histology, and the combination of chemotherapy and/or surgery to see the influence on the results following radiation therapy as prognostic factors. Of these factors, only performance status and response after radiation therapy showed statistical significance (p<0.05).