Progress achieved during the last three decades in medical and surgical treatment of infants and children with congenital heart disease has resulted in a significant number of patients surviving to adulthood. The complexity of the basic malformations in addition to the superimposed surgical interventions makes accurate diagnostic imaging essential. The scope of information obtainable from high-quality TEE supports its use in the follow-up of operated and unoperated adult patients, as well as in surgical and interventional procedures. Application of the segmental analysis of anatomy is as important during TEE as it is during TTE. Supplemental transthoracic 2-D and spectral Doppler flow measurements may be needed when poor beam alignment during TEE precludes accurate gradient determinations. Although, to date, most reports of TEE in patients with congenital heart disease have involved children and adolescents, the informational advantage is potentially greater in older adolescents and adults in whom transthoracic windows are frequently limited. In our experience with 125 TEE studies in adult patients with congenital heart disease (the majority using a biplane probe), horizontal plane TEE imaging provided important additional information concerning pulmonary venous connections, atrial baffle function, atrioventricular anatomy and function, left ventricular outflow tract lesions, and great artery positional relationships. Vertical plane TEE enhances imaging of systemic and pulmonary venous connections, atrial situs, venosus atrial septal defects, atrioventricular anatomy and function, and the ventricular septum and outflow tracts and is essential for complete assessment of complex right ventricular outflow tract anatomy, ventriculoarterial alignment, and the sizing of all aortic segments in coarctation of the aorta.