A 2-year-old boy underwent surgical repair of tetralogy of Fallot. Topical cooling of the heart with ice slush was used during the operation. Diaphragmatic paralysis occurred after the operation, inducing severe respiratory distress. To avoid repeated intubation and tracheostomy, the patient was placed on nasal mask bilevel positive airway pressure (BiPAP) ventilation. After ventilatory support with BiPAP for 40 days, the patient recovered spontaneously from the paralysis. No sedation was required during this time. This report illustrates the usefulness of BiPAP for a pediatric patient with diaphragmatic paralysis after cardiac surgery.