I-123 labeled methyl-branched fatty acid, BMIPP, has been used mainly in Europe and Japan for the evaluation of various cardiac diseases. BMIPP uptake abnormality is usually more prominent tan perfusion, representing discordant BMIPP uptake less than thallium. This finding is observed in various cardiac disease conditions such as acute myocardial infarction, stable and unstable angina, hypertrophic and dilated cardiomyopathies. Many BMIPP studies combined stress thallium imaging in patients with coronary artery disease and hypertrophic cardiomyopathy demonstrated that such discordant BMIPP uptake less than thallium is related to stress-induced ischemia as evidenced by reversible thallium defect after exercise. BMIPP imaging is able to detect metabolic alteration in the heart which is not available by perfusion imaging alone.