The data of documentation of 267 operatively treated patients with lung cancer are shown in a retrospective study. The patients were treated in the clinic for tuberculosis and respiratory diseases of the faculty hospital Plzen. In 50% of the cases the results of histological and cytological examinations correspond with the surgical observations. Results of the pneumomediastinography and the computed tomography of the lung and mediastinum correspond with findings through the operation in 71% and 73% respectively. Through out the last three years the reliability of the cytological diagnosis was increased significantly (p less than 0.01).