introduction: abnormalities of the airway often present with stridor. the main cause in neonates and infants are the congenital defects of the larynx. the specific etiologic diagnose can be just obtained through fibronasolaryngobroncoscopy, which is necessary for the correct management of this children. study design: clinical prospective and descriptive cross-sectional study. aim: to describe the main causes and associated clinical findings of stridor in children presenting to our hospital. material and method: a prospective investigation was performed from march 2000 to april 2001 to study all children evaluated at the department of pediatric othorrinolaryngology of hospital da crian？a santo ant？nio with the inclusion criterion of stridor. these patients were examined according to a priori defined protocol, which includes besides questions about history, physical examination and associated comorbities, a standard fibronasolaryngobroncoscopy examination. results: a group of 125 children (69 male and 56 female) were evaluated. the mean age at inclusion was 19 months. most patients came from intensive care unit. almost all cases had comorbidities, long-term endotracheal intubation been the most common finding. the most frequent diagnose were laryngomalacia (n=51, 40.8%) and subglottic stenosis (n=22, 17.6%). conclusions: even in the presence of a more select sample than the great international series, we also found congenital anomalies of the larynx as the main cause of stridor. it was difficult to differentiate between congenital and acquired subglottic stenosis in some cases with a history of endotracheal intubation. the presence of comorbidities is frequent and may help to select the patients who will need endoscopic evaluation.