Three patients with vascular sling were studied by two-dimensional and color Doppler echocardiography and angiocardiography. One case was associated with atrial septal defect and another with tetralogy of Fallot and patent ductus arteriosus. The third case had no associated intracardiac anomalies. Color Doppler flow mapping was performed in all three patients, and transesophageal echocardiography was studied in two patients. Color Doppler echocardiography showed the characteristic features of this congenital anomaly in all three patients, especially in detecting the site of anomalous origin of the left pulmonary artery. A small patent ductus arteriosus was misinterpreted as the normal left pulmonary artery in one patient. Small pulmonary arteries in the patient with tetralogy of Fallot made the diagnosis difficult. Using transesophageal echocardiography, we clearly identified the trachea, esophagus, and abnormal left pulmonary artery.