Between 1991 and 1995, 5.520 rigid bronchoscopies were performed in children al the Bronchologic-Pulmonan Lab of our Institute; a Iracheal bronchus was incidentally found in 21 patients (0.98%). Their ages at the time of bronchoscopy ranged from 3 months to 14.5 years. Indications for bronchoscopy were: recurrent bronchitis not responding to conventional therapy with or without wheeze; unexplained cough; stridor; and recurrent pneumonia. Tracheal bronchus was found in the lower third of the trachea in the majority of patients Tracheal duplication of the right upper lobe (A-type). supernumerary tracheal bronchus (B-type). and tracheal transposition of the right upper lohe (E-type) were described in 8, 10, and 3 patients, respectively. Surgical resection of the tracheal bronchus was not considered necessary in any of the patients. Concomitant airway malformations included dynamic collapse of the trachea as a consequence of cartilage hypoplasia (traeheomalacia) in 3, rigid stenosis in 2, and dynamic collapse of the left main hronchus as a consequence of cartilage hypoplasia in 7 patients; stenosis of ring cartilage, stenosis of truncus intermedius. and stenosis of left lower lobe bronchus in respective cases. Extrapulmonary malformations included congenital heart disease, situs inversus solilus, dextrocardia, diaphragmatic hernia, and pectus excavatum in respective cases. We concluded that tracheal bronchus is regularly but not frequently found in the patients with chronic chest symptoms, that surgical resection of a tracheal bronchus is unnecessary if there is no local pathologic process in the adjacent lung tissue, and that significant associated pulmonary and extrapulmonary developmental disorders are likely with tracheal bronchus.