Diaphragmatic paralysis may cause life threatening respiratory distress especially in infancy. A case is reported of a 32 week gestation infant with bilateral phrenic nerve palsies and associated brachial plexus injury who remained severely compromised despite spontaneous recovery of the right hemidiaphragm after 13 weeks. Operative plication of the left hemidiaphragm produced a marked improvement. Surgery should be considered after an adequate trial of expectant management in symptomatic patients.