Laryngotracheomalacia usually is a self-limited disease causing only noisy respiration. This report describes an infant born with a severe form of this anomaly who manifested cor pulmonale and congestive heart failure by 29 months of age. Suprasystemic pulmonary artery pressures were noted at the time of the initial cardiac catheterization. The child improved clinically after tracheostomy, and a repeat cardiac catheterization at 4 years of age showed a marked decrease in pulmonary artery pressure. Though a frequent cause of stridor in infancy, to our knowledge laryngotracheomalacia has not been reported as associated with cor pulmonale.