Cor triatriatum dexter is a rare cardiac congenital malformation in which a membrane divides the right atrium into two chambers. We describe one case of isolated cor triatriatum dexter, symptomatic for severe central cyanosis, in which the membrane was identified before surgery by means of transthoracic echocardiography alone, and successfully removed surgically at 1 month of life. We discuss this case and review the literature.