Echocardiography is a useful and reliable tool for the clinical assessment of the cyanotic neonate. It can be applied rapidly without compromising even the critically ill neonate. Hypoplastic left and right heart syndromes can be diagnosed or excluded echocardiographically. The diagnostic exclusions of total anomalous pulmonary venous drainage and complete transposition of the great arteries in the neonate with cyanosis remain difficult challenges for the echocardiographer because of the variability of their anatomic and hemodynamic presentations.