Twenty-six children with eventration (congenital in 10, resulting from birth trauma in four, and resulting from operative phrenic nerve injury in 12) under 15 months of age were evaluated at a single institution in a 5 year period. There was a high incidence of significant associated anomalies and prematurity. All operative phrenic nerve injuries occurred in patients under 3 months of age, and they were most common in patients undergoing Blalock-Taussig shunt. Plication (12 thoracic, nine abdominal) was performed in 21 patients, 19 of whom had respiratory distress or were ventilator dependent. Repeat plication was required in four patients. All long-term survivors were extubated within 1 week of plication. Of 21 patients undergoing plication, 14 (67%) died. Death was attributed directly to complications of eventration in three patients and was a contributing factor in nine patients. We reached the following conclusions: The incidence of operative phrenic nerve injury in infants undergoing lateral thoracotomy, particularly for Blalock-Taussig shunt, is higher than generally appreciated; plication is a safe procedure as performed by either an abdominal or thoracic approach; failure to achieve extubation within a week of plication is an ominous prognostic sign; mortality in patients with eventration in the presence of major associated conditions may be high despite plication.