Unguarded tricuspid regurgitation (TR) due to a flail tricuspid leaflet is a rare condition of newborn cyanosis. A high perinatal mortality has been associated with this fatal condition. But, there are feasible surgical repairs to improve survival. We report the case of a male full-term neonate with intractable hypoxia. He had profound tricuspid insufficiency and leaflet prolapse caused by a ruptured papillary muscle supporting the anterior leaflet of the tricuspid valve. He presented with severe cyanosis and respiratory distress immediately after birth. Despite medical management, the pulmonary vascular resistance was not decreased and a low cardiac output persisted. Initial stabilization was accomplished with nitric oxide and extracorporeal membrane oxygenation. The tricuspid valve repair surgery was successfully performed subsequently. TR resulting from papillary muscle rupture is a potentially lethal condition. Timely diagnosis and proper surgical treatment can be lifesaving.