In detecting, localizing and quantitating cardiac shunts, radionulide angiocardiography has been known to be a simple and safe method compared with oxymetry method. To ascertain the availability of the results obtained by radionuclide angiocardiography for the evaluation of patients with cardiac shunt, author compared the Qp/Qs ratios(pulmonary to systemic flow ratios) obtained by radionuclide angiocardiography with the results of oximetry method in 40 patients with left to right shunt, and also compared the results of radionuclide angiocardiography examined before and after shunt operation in 8 patients. The results were as follows: 1) Of the 161 patients examined radionuclide angiocardiography, 98 were thought to have cardiac shunts: right to left shunt id 27, left to right shunt in 71. Of the 71 patients who had left to right shunt, 40 who were examined with both radionuclide angiocardiography and oxymetry had following congenital heart disease: VSD in 21, ASD in 9 and PDA in 10. 2) Comparison of Qp/Qs ratios obtained during radionuclide angiocardiography and oxymetry revealed good correlation (linear regression analysis yielded correlation coefficient of 0.80) in 32 patients whose Qp/Qs ratio obtained during oxymetry were below 3.0, but very poor correlation in 8 patients whose Qp/Qs ratios were above 3.0 3) Radionuclide angiocardiography is a relatively safe and simple method in postoperative evaluation of patients with cardiac shunt.