Episodes of wheezing are very common in infancy. In pediatrics, indications for flexible bronchoscopy include prolonged wheezing, where airway; abnormalities such as malacia disorders, tracheobronchial abnormalities, and vascular ring may be found. The study was performed to determine the diagnostic use of flexible bronchoscopy in wheezy patients who were previously administered bronchodilators and steroids for asthma and whose symptoms recurred or were not improved at all. Infants with wheezing were identified and collected over a 3-year period at the pediatric pulmonology unit. Flexible bronchoscopy, was performed for diagnostic purposes in 34 (24 boys and 10 girls) patient.,; with wheezing who were previously treated for asthma. The mean age for the onset of the symptoms was 2.5 months (0-12 months), and the mean age of bronchoscopic assessment was 9 months (45 days-48 months). A definitive diagnosis was made by bronchoscopy in 29 (85%) patients. Functional abnormalities in 15 patients (malacia in 9. tracheal dyskinesia in 3, and both in 3 patients), structural abnormalities in 5 patients (bronchial abnormality, in 2, subglottic stenosis in 2, and obliterative-like lesion at the orifice of right bronchus in 1), and coexistent structural and functional abnormalities in 9 patients were present. Bronchoscopy revealed normal findings in five patients. Structural and functional airway abnormalities are commonly found in children with wheezing and should be considered in the differential diagnosis of persistent and prolonged wheezing. Bronchoscopy should be performed in patients who remain symptomatic despite treatment for asthma.