To evaluate the clinical efficacy of 99mTc-MIBI myocardial tomography for detecting coronary artery disease, 34 consecutive patients who underwent both 99mTc-MIBI study and coronary arteriography were included in the present study. Ten without and 24 with significant coronary artery disease were documented by coronary arteriography. The overall sensitivity and specificity of 99mTc-MIBI study for detecting coronary artery disease were 91.8% (22/24) and 80.0% (8/10), respectively. In subset studies, 16 of 17 (94.1%) patients with previous myocardial infarction and 6 of 7 (85.7%) patients with significant CAD but without MI were identified as abnormal. Reversible perfusion abnormalities were shown in 4 of 5 patients undergoing both exercise and rest studies. Rest perfusion abnormalities were shown in 2 patients with unstable angina pectoris who underwent only rest study. In conclusion, 99mTc-MIBI myocardial tomography provides a reliable method for detecting coronary artery disease. Rest study has high sensitivity for identifying patients with MI, and exercise/rest study can identify patients with significant CAD but without MI.