The most important surgical goal during potentially curative surgery for non-small cell lung cancer (NSCLC) is a macroscopic and microscopic radical resection (R0-resection). Studies reporting on recurrence and long-term survival mainly comprise patients with completely resected NSCLC (R0-resection). However, there is limited data on incidence, treatment and prognosis of patients with microscopic residual tumour tissue at the bronchial resection margin (R1-resection). Furthermore, the definition of an R1-resection of the bronchial resection margin is not uniform in literature. Based on 19 studies published between 1945 and 2003 with a substantial number of included patients with resected NSCLC, the incidence of an R1-resection of the bronchial resection margin is approximately 4-5% (range 1.2-17%) of all lung resections. Divided into the localisation of the microscopic residual disease, survival of patients with carcinoma in situ (CIS) at the bronchial resection margin is comparable to the survival after a radical resection. The prognosis is negatively influenced in case of microscopic mucosal residual disease. Survival is even worse in patients with peribronchial residual disease; 1- and 5-year survivals range between 20-50% and 0-20%, respectively. This poor prognosis is because peribronchial residual disease, in 75-85% of the patients, is associated with mediastinal lymph node metastasis. According to the stage, survival of patients with stage I and II NSCLC and an R1-resection of the bronchial resection margin is significantly worse as compared to stage-corrected survival after a radical resection. In these patients, survival is limited due to local recurrence. The negative effect of an R1-resection of the bronchial margin in stage III NSCLC is limited, as these patients die due to disseminated disease (distant metastasis) before local recurrence occurs. A conservative approach with frequent bronchoscopic surveillance is justified for CIS. For patients with microscopic residual disease at the bronchial margin and stage I and II NSCLC, further treatment has to be considered. Adjuvant treatment in patients with stage III NSCLC has no proven benefit in terms of survival.