The entitiy of hamartoma of the lung is defined and frequency, location, tissue components, and roentgenographic appearance are described. The clinical significance of this disease in one case of endobronchial location is discussed. It is reported about an own observation of an endobronchial, pendulous, polypoid chondrolipoma (hamartoma) which is located near the tracheal bifurcation. The following points about roentgenological procedures and diagnostic interpretation are concluded: 1. Indirect signs for occlusion of the right main stem bronchus by a pendulous polypoid hamartoma are a small-appearing right hilus and the overinflation of the right upper lobe caused by a valve-like mechanism. 2. The postoperative overinflation is located beyond the stalk of this lesion which originates in the right upper lobe, although the mass of this pendulous tumor is located in the right main stem bronchus, respectively in the right lower lobe bronchus (documented by tomography and surgery).3. The recognition of shape and inferior limitation of polypoid endobronchial neoplasmsis achieved best by tomography which is a simple, innocuous diagnostic procedure. Bronchoscopy and biopsy clarify preoperatively the criteria of the lesion.4. Bronchography of poststenotic areas of the lung in polypoid pendulous endobronchial neoplasm is contraindicated on account of threatening respiratory insufficiency.5. Development of an alternating broncho-tracheal syndrome must be considred in patients which undergo endoscopy in anesthesia.