Objective: Accurate preoperative staging is essential to provide the best treatment for lung cancer. The objective of the present study was to determine agreement between preoperative and surgical pathological staging and to analyse the impact of any disparity on treatment. Methods: This is a descriptive study of a series of 176 lung cancer cases treated by surgery between 2005 and 2007. Preoperative staging was based on clinical information and computed tomography (CT), positron emission tomography (PET), PET-CT, bronchoscopy and mediastinoscopy. In all cases, surgical pathological staging was based on the analysis of surgical samples and the findings during surgery. Both preoperative and pathological stage determination were based on the TNM (tumour, node, metastasis) classification established in 1997. Concordance was measured by calculating agreement rates and the kappa value. Results: Preoperative and surgical pathological staging agreed in 102 cases, an agreement rate of 58% and kappa value of 0.54 (95% confidence interval (CI) 0.44 0.63). The highest kappa value (0.68, 95% CI 0.53 0.82) was obtained in stage IA patients. Patients who underwent PET or PET-CT had a better kappa index (0.56, 95% CI 0.45 0.67, vs 0.39, 95% CI 0.21 0.56). Surgical pathological staging validated surgery in 145 cases (82%), while 21 (12%) were revised to stage IIIA N2 and 10 (6%) to non-surgical stages. Conclusions: Global agreement between preoperative and surgical pathological staging was moderate. The best agreement was found in stages IV and IA.