The delineation of the structural and functional abnormalities of the fetal heart by echocardiography has led to the emergence of a new and vital subspecialty, that of fetal cardiology. Its practitioners are from disciplines such as genetics, obstetrics, and pediatrics, the common interests of which in the well-being of the unborn child have converged as technologic advances in ultrasound have enabled detailed evaluation and sometimes treatment of fetal hemodynamic abnormalities. Each discipline forms an entry point for the identification and referral of the high-risk patient or fetus with a suspected abnormality. As has been shown obstetric cardiac screening of the general population with ultrasound provides the highest yield of cardiac malformations when suspicious findings are referred to a subspecialist in fetal cardiac sonography. As we study the pathogenesis of congenital defects, it is likely that hitherto unidentified high risk populations will be found. The future holds the possibility of meaningful surgical interventions that may change the dismal outcome of fetuses with certain, now lethal cardiac malformations. Patients with hydrops fetalis due to congenital complete heart block are almost certain to die. Intrauterine cardiac pacing has been attempted and is a potentially life-saving procedure. Patients in whom pulmonary underdevelopment occurs because of the cardiac enlargement associated with some types of pulmonary atresia could potentially benefit from intrauterine surgery such as valvotomy. Serial fetal echocardiographic examination of the developing heart with higher resolution equipment during the first trimester may one day pinpoint the exact moment of teratogenesis and lead to more specific treatments designed to restore normal embryogenesis. Such examinations will, when known to be safe themselves, at the very least significantly advance our knowledge of normal cardiac embryogenesis and pathogenesis.