To determine whether technetium-99m hexakis-2-methoxy isobutyl isonitrile (99mTc-MIBI) myocardial scintigraphy is a superior method in the detection of coronary artery disease, exercise and rest 99mTc-MIBI planar and SPECT scintigraphy were performed on 27 patients with coronary artery disease. When 99mTc-MIBI (555 MBq (15 mCi)) was injected, first-pass radionuclide angiography (FPRNA) was simultaneously performed by a new mobile multicrystal gamma camera (SIM-400), and LV function (LVEF) was evaluated quantitatively. Visual semiquantitative detection of coronary lesions using 99mTc-MIBI images showed superior accuracy to that obtained using 201TlCl images. 99mTc-MIBI SPECT images were particularly useful in diagnosing LCX and RCA lesions. Moreover, the simultaneous assessment of perfusion and left ventricular function by 99mTc-MIBI FPRNA proved to be useful in the diagnosis of multi-vessel disease. In summary, 99mTc-MIBI SPECT scintigraphy with simultaneous assessment of left ventricular function showed better diagnostic accuracy than 201TlCl myocardial scintigraphy.