Simultaneous dual-isotope SPECT with 99mTc-methoxy isobutyl isonitrile (MIBI) and 123I-beta-methyl iodophenyl-pentadecanoic acid (BMIPP) was performed in 25 patients with ischemic heart disease. ECG-gated myocardial SPECT was acquired following the injection of MIBI (555 MBq) and BMIPP (148 MBq). Both MIBI and BMIPP scans provided high-quality myocardial images. Then, myocardial count increase rate (%WT = ES-ED/ED x 100) was calculated as an index of left ventricular contraction using MIBI gated SPECT data. The %WT was well correlated with severity scores of both MIBI image (r = -0.70) and BMIPP image (r = -0.72). Thus, ECG-gated dual-isotope SPECT with MIBI and BMIPP was considered to be useful method for assessment of left ventricular contraction as well as myocardial perfusion and fatty acid metabolism.