The assessment of congenital aortopulmonary communications by transthoracic echocardiography may be suboptimal, particularly postoperatively, due to limited acoustic windows. We performed intraoperative transesophageal echocardiograms in six patients with eight proven systemic-pulmonary communications. Diagnosis included truncus arteriosus (1), aortopulmonary window (1), Waterston anastomosis (3), central Gore-Tex shunt (1), and modified left Blalock-Taussig shunt (2). All communications were accurately demonstrated by transesophageal echocardiography (TEE). The transesophageal technique also provided an assessment of the size of the aortopulmonary communications and the proximal pulmonary arteries. In addition, the gradient across some of the communications could be accurately estimated utilizing the high pulse repetition frequency Doppler. On the other hand, only two of the seven aortopulmonary communications were detected by transthoracic echocardiography. Postoperatively, transesophageal imaging demonstrated unobstructed conduit in five of five patients who underwent conduit repair, as well as intact closure of aortopulmonary communications and concomitant closure of ventricular septal defects.