Abstract. We report two cases of term male infants with suspected pulmonary hypoplasia, who could not be managed successfully with conventional mechanical ventilation. Both responded to rescue support with high frequency jet ventilation (HFJV) using an optimal positive end expiratory pressure strategy. One infant had the oligohydramnios sequence secondary to posterior urethral valves. The second infant was diagnosed prenatally with a severe right-sided congenital diaphragmatic hernia. We summarize the literature on the use of HFJV to support infants with severe pulmonary dysfunction. Unique air flow dynamics of HFJV may enable better gas exchange with less barotrauma, less volutrauma and ventilation at lower mean airway pressure. Our experience and the available literature suggest that HFJV appears to offer a unique advantage over conventional ventilation in such infants.