Subglottic stenosis is the most common cause of chronic airway obstruction. It results in prolonged tracheal cannulation of infants and children. Following the widespread adoption over the past 20 years of prolonged intubation for respiratory support in neonates, the incidence of acquired subglottic stenosis increased dramatically. On January 1, 1987, we began a 3-year prospective study to delineate potential etiologic factors involved in the development of subglottic stenosis in neonates. The present study analyzes data from 289 infants. Relationships between birth weight, gestational age, endotracheal tube size, duration of intubation and ventilation, number and difficulty of intubations, and the subsequent need for medical and surgical therapy are discussed. Whole organ larynges from autopsy specimens provide histological correlation.