Severe tricuspid regurgitation resulting from a flail leaflet is a rare cause of neonatal cyanosis. We report a neonate with profound cyanosis and severe tricuspid regurgitation caused by a rupture of the papillary muscle supporting the anterior leaflet, without other structural heart defects. Ductal patency could not be established. The repair of the tricuspid valve was performed after initial stabilization by using extracorporeal membrane oxygenation.