OBJECTIVE: We performed a retrospective study evaluating the effect on survival of different sites of microscopic residual disease at the bronchial resection margin after surgical intervention for non-small cell lung cancer. METHODS: Survival of patients with different sites of residual disease was compared with survival of patients with curative resections, taking the pathologic TNM stage of the tumor into consideration. RESULTS: There was a trend for patients with stage I and II non-small cell lung cancer with residual disease limited to the epithelium and with peribronchial invasion to behave like patients with complete resections (61% and 41% five-year survival for stage I and II disease, respectively). This contrasts with patients with submucosal invasion and lymphatic infiltration, among whom there were no survivors at 5 years. There was no difference in survival between curative resections and residual disease of any type when the tumor was stage III or IV. CONCLUSIONS: In patients with stage I and II disease, when residual disease consists of submucosal invasion or lymphatic infiltration, specific and aggressive treatments to clear residual margins might be contemplated because of their possible adverse effect on survival. This contrasts with patients with stage III and IV disease, in whom survival is more related to the stage of the primary tumor than to residual disease.