The left ventricular ejection fractions of 53 patients were determined from multi-image cardiac blood pool scintigrams in the left anterior oblique position utilizing a microcomputer and floppy disc. These date were compared to ejection fractions obtained at cardiac catheterization in the right anterior oblique position. The ejection fraction obtained by radionuclide technique was comparable to that obitained by contrast angiography in the 53 patients with an r = 0.93. Forty-five patients with coronary artery disease showed an r = 0.92. In the coronary artery group with regional wall dysfunction, the correlation was r = 0.89.