An infant with pneumomediastinum due to mechanical ventilation was successfully treated using high frequency oscillatory ventilation (HFOV). The 3-month-old male had undergone ligation of a patent ductus arteriosus and suffered from barotraumatic pneumomediastinum in the postoperative period. Computed tomography of the chest confirmed the diagnosis. While using conventional mechanical ventilation the respiratory failure worsened. HFOV was instituted and the patient improved. A lower airway pressure by this mode of ventilation provided significant advantages in the patient with an air leak. He was subsequently extubated and discharged home.