Diaphragmatic paralysis has been mentioned infrequently as a cause of respiratory symptoms in children. During a three-year period, diaphragmatic paralysis has occurred in 12 neonates following birth trauma (six) or thoracotomy (six) and in four older children following thoracotomy. Spontaneous recovery occurred in all four older children and in five of the 12 neonates. Although two neonates became asymptomatic despite persistent paralysis, the remaining five neonates required prolonged intermittent positive-pressure breathing; two eventually died of secondary pneumonia, and three became asymptomatic only after plication of the affected diaphragm.