We analyzed 96 patients who had surgery with T1N0M0 or T2N0M0 nonsmall cell lung cancer (NSCLC) to identify survival rates and recurrence patterns in well-staged patients and to evaluate adjuvant therapy. Preoperative staging included chest x-ray, gallium 67 scanning, and bronchoscopy in all patients. At thoracotomy, multiple mediastinal lymph node sites were routinely sampled. The results included an operative mortality rate of 5.2%, and the actuarial 5-year survival rate of all patients was 70.0%. Survival of T1N0 (n = 44) and T2N0 (n = 47) patients was 72.1% and 68.3%, respectively (p = NS). Survival was not affected by type of surgery, cell type, sex, age, or race. Late death was due to recurrence in 12 patients, a new airway malignancy in three, and a noncancer problem in six. Disease recurred in 15 patients: four (9.1%) T1N0 patients versus 11 (23.4%) T2N0 patients, p less than 0.05. Recurrence was local in four patients and distant in 11. Second lung cancers developed in six patients at a mean interval of 65.7 months after resection. A prospective, randomized trial of systemic immunotherapy with bacillus Calmette-Guerin (BCG) skin scarification was carried out in 29 patients. Survival in those patients receiving BCG was 85.9% compared with 63.9% for control subjects (p = 0.075) and 69.6% for patients not in the study (p = 0.077). The following conclusions can be made: Resection for well-staged, modified stage I NSCLC results in a 5-year survival rate of 70%. Nearly half the deaths are unrelated to recurrence of the original cancer. Recurrences are more frequent in T2N0 patients, but there is no survival difference compared with T1N0 patients. Systemic recurrences are more frequent than local recurrences, and there is an appreciable incidence of second lung cancers. Adjuvant chemotherapy or radiation therapy does not seem justified, but systemic immunotherapy holds sufficient promise to warrant further investigation.