Cor-triatriatum dexter is an extremely rare congenital anomaly, in which right atrium is divided into 2 halves by a septum giving rise to 3 atrial chambers. We report here a case of cor-triatriatum dexter who presented at 3 days of life with tachypnea and did not respond to antibiotics. Echocardiography revealed ostium secundum atrial septal defect (ASD) with right to left flow, intact interventricular septum (IVS), severe tricuspid regurgitation with pulmonary arterial hypertension and a membranous structure dividing right atrium into 2 halves with good biventricular function. The patient improved with sildenafil and anti-failure medication. This case of cor-triatriatum dexter presenting with pulmonary hypertension, tricuspid regurgitation and ASD added to the new spectrum of cor-triatriatum dexter.