This 45-year-old white male was evaluated for congestive heart failure initially ascribed to a rapidly progressive cardiomyopathy. Both radionuclide ventriculography and echocardiography correctly identified a left ventricular pseudoaneurysm as the cause for heart failure. Thallium-201 scintigraphy, by demonstrating a large perfusion defect, suggested a large ostium of the pseudoaneurysm. Following resection of the false aneurysm, a Dacron prosthesis was required to close a large posterior wall defect. We conclude that both radionuclide ventriculography and echocardiography can independently demonstrate a left ventricular pseudoaneurysm. The combined noninvasive approach is able to delineate various anatomical aspects of the pseudoaneurysm and help in planning adequate surgical intervention.