Radiologic imaging of the chest has been proven to be unreliable in diagnosis of mediastinal lymph nodes and tumor invasion of cancer and has several other limitations. The view of the endoscopist however is limited to the lumen and the internal surface of the airways. Processes within the airway wall and outside the airways can only be assessed by indirect signs. In addition, many processes also involve the parabronchial structures. Especially in malignancies, this can be of importance for the fate of the patient. Therefore, expanding the endoscopist’s view beyond the airways is essential. Transthoracic ultrasound is insufficient for imaging of the paratracheal and hilar structures, and endoesophageal ultrasound (EUS) also incompletely depicts the pretracheal region and the hilar structures because of limited contact and interposition of the airways. Since 1999, radial EBUS (endobronchial ultrasound) offers another approach to overcome some of the limitations.