Mediastinal and hilar masses not associated with an endoscopically visible lesion and processes involving only the bronchial submucosa are often difficult to diagnose despite the ability to obtain cytologic and histologic samples via the flexible fiberoptic bronchoscope; necrotic endobronchial lesions are often suspected to be tumorous but may not be biopsied for fear of creating further and uncontrollable bleeding. Diagnostic material from such lesions can be obtained by aspiration with a thin needle localized via the bronchoscope at the site of the lesion and then inserted through the bronchial wall into the mediastinum, hilum or bronchial submucosal area. Not only can the question of neoplasia be answered by this technique, but staging in an inexpensive and non-morbid way can be accomplished. Indications for transbronchial fine needle aspiration, the excellence of cytologic samples thus obtained and the problems encountered using existing disposable equipment are discussed. Four cases are reported briefly as examples of the use of the technique.