The SPECT unit using a 3 heads camera (PRISM-3000) has an advantage over the conventional one head camera SPECT unit because it can complete full circle scans (360 degrees scans) within a short time, and because the non-circular orbit of the camera heads fitting the individual form of the body has improved the spatial resolution. In addition, the high speed data processing has reduced the time for scan, enabling the three dimensional imaging system clinically applicable. In the present study, this modern technique was used to examined the myocardium in patients with ischemic heart disease so as to evaluate it for usefulness and depict problem to be solved. In patients with myocardial infarction, images obtained with a PRISM-3000 machine could provide more objective information on infarcts than conventional images. In patients with angina pectoris, delayed images obtained 3 hours after exercise by the new method were superior to conventional ones in power of demonstrating redistribution. The setting of the threshold for ischemic lesions at 40-50% hampers the assessment of the severity of ischemia. A new program should be introduced to solve this problem.