Fetal echocardiography has assumed an increasingly important role in the diagnosis of structural heart disease. Recently, the usefulness of this technique as a tool with which to observe the prenatal natural history of congenital heart disease has been appreciated. The application of spectral and color Doppler ultrasonographic interrogation has added to our ability to assess the integrity of the fetal and placental circuit. Only when we can consistently and accurately diagnose congenital heart diseasein uterowill we be able to successfully apply prenatal treatment for this condition.