PURPOSE: Patients with pulmonary atresia with ventricular septal defects(PAVSD) have been a formidable surgical challenge. The source of pulmonary blood flow and vascular architecture are important in managing the surgical process. This study aimed to evaluate the usefulness of echocardiography in this process. METHODS: This study was prospectively designed to define the role of echocardiography in PAVSD. Non-invasive evaluations including echocardiography were done, catheterization/angiography was performed the next day and the results were compared with those of echocardiography. The study population consisted of 9 patients, diagnosed as PAVSD in our hospital, from Jan. 1995 to Dec. 1997. RESULTS: Pulmonary blood was supplied via ductus arteriosus, in 3 patients(group 1), and in the other 6 patients, via major aortopulmonary collateral arteries(MAPCA)(group 2). The characteristic findings of group 2 were cardiac murmur heard in the back area(3 cases), and abnormal pulmonary arborization pattern(2 cases). The echocardiographic diagnosis of source of pulmonary blood flow was correct in all cases except one case-who had had two previous shunt surgeries and additional MAPCAs. In group 2, the presence of pulmonary confluence was predicted in 3 out of 4 cases. The mean number of MAPCAs found by echocardiography was 2.3+/-1.2 and by angiography, 3.5+/-1.4. CONCLUSION: In evaluation of PAVSD patients, near complete characteristics of pulmonary blood supply were identified by echocardiogram. Using it, practitioners can make decisions for shunt surgery or the need for further evaluations, including cardiac catheterization which can be more easily executed with previous echocardiographic data.