Some studies report a high risk of death from intercurrent disease (DID) after postoperative radiotherapy (XRT) for non-small-cell lung cancer (NSCLC). This study determines the risk of DID after modern-technique postoperative XRT. A total of 202 patients were treated with surgery and postoperative XRT for NSCLC. Most patients (97%) had pathologic stage II or III disease. Many patients (41%) had positive/close/uncertain resection margins. The median XRT dose was 55 Gy with fraction size of 1.8 to 2 Gy. The risk of DID was calculated actuarially and included patients who died of unknown/uncertain causes. Median follow-up was 24 months for all patients and 62 months for survivors. A total of 25 patients (12.5%) died from intercurrent disease, 16 from confirmed noncancer causes and nine from unknown causes. The 4-year actuarial rate of DID was 13.5%. This is minimally increased compared with the expected rate for a matched population (approximately 10% at 4 years). On multivariate analysis, age and radiotherapy dose were borderline significant factors associated with a higher risk of DID (P =.06). The crude risk of DID for patients receiving less than 54 Gy was 2% (4-year actuarial risk 0%) versus 17% for XRT dose > or = 54 Gy. The 4-year actuarial overall survival was 34%; local control was 84%; and freedom from distant metastases was 37%. Modern postoperative XRT for NSCLC does not excessively increase the risk of intercurrent deaths. Further study of postoperative XRT, particularly when using more sophisticated treatment planning and reasonable total doses, for carefully selected high-risk resected NSCLC is warranted.