Transesophageal echocardiography using Doppler color flow mapping with both single plane transverse and longitudinal pediatric probes was performed in 127 infants and children both intraoperatively and postoperatively. The 127 patients ranged in age from 1 day to 18 years (mean 37 months) and in weight from 2.4 to 45 kg (mean 13.2); 157 studies were successfully performed (100% of attempted) with no complications.Transesophageal two-dimensional echocardiography combined with pulsed wave Doppler ultrasound and color flow mapping provided detailed morphologic as well as physiologic information, with additional information provided overall in 56% of the cases. Typical limitations of single-plane transverse imaging were overcome using a prototype longitudinal-axis pediatric probe. Both left and right ventricular outflow tracts, distal pulmonary arteries and all of the interventricular and atrial septa were visualized. Assessment of surgical repair intraoperatively as well as assessment postoperatively for cardiac function, residual intracardiac shunts, residual valvular sequelae and other hemodynamic events was important and easily performed in an otherwise inaccessible patient.Transesophageal echocardiography in infants and in small children is a valuable “noninvasive” imaging technique that offers important additional and complementary information.