Conventional imaging procedures proved to be insufficient for staging of lung cancer especially with respect of N-stage, infiltration of mediastinal structures and early lung cancer. As also the view of the endoscopist is restricted we developed the new method of endobronchial ultrasonography (EBUS) as adjunct to conventional bronchoscopy. The initial technical problems were solved by development of a balloon catheter for application of miniaturized 20 MHz probes. EBUS is a new technology that can be easily applied and is well tolerated. It improves the results of bronchoscopy in addition to conventional diagnostic procedures. Further developments will be made in future to improve the application of ultrasound in chest medicine.