This study was carried out in the Departments of Pediatrics and Nuclear Medicine at Hacettepe University Faculty of Medicine between April 1986 and March 1988 with the aim of detecting left-to-right shunts in 70 patients with isolated ventricular septal (VSD) defect, isolated atrial septal defect (ASD) and patent ductus arteriosus, by using the radionuclide technique together with contrast echocardiography. In some patients, the results were confirmed by both cardiac catheterization and angiocardiography. Most of the data were confirmed during surgery. A good correlation was found between the results of contrast echocardiography and radionuclide angiography. The difference between the QP/QS value and the grade of positive contrast effect was tested statistically and "p" was found to be less than 0.001. Therefore, we conclude that these methods could be applied together to determine the indication for surgery in cases with ASD or VSD.