Tc-99m MIBI(methoxy isobutyl isonitrile) is newly introduced cationic myocardial perfusion agent. For its favorable dosimetry, up to 30mCi of Tc-99m MIBI can be used in a patient, Therefore, unlike T1-201, first-pass ejection fraction, ventricular wall motion, and SPECT studies are readily evaluated using Tc-99m MIBI on patients who are undergoing myocardial perfusion study. Nineteen indivisuals entered into this study and 9 of 19 had T1-201 myocardial scintiscan. For the detection of myocardial ischemia, an IV dipyridamole with hand-grip or bicycle exercise was used. Tc-99m MIBI scintigraphic findings are compared to patients 'EKG' T1-201 scans and coronary angiograms. The results were summerized as follows: 1. In 9 cases, Tc-99m MIBI studies were comparable to T1-201 scintiscans. 2. In the remaining 10 cases, Tc-99m MIBI images were correlated well with clinical pictures, EKG,and angiographic findings. 3. Using tc-99m MIBI, one can easily obtain fist-pass ejection fraction, ventricular wall motion and SPECT studies. It was concluded that Tc-99m MIBI images are superior in quality than T1-201 images mainly due to high photon yield and ideal energy of Tc-99m MIBI.