Cardiac PET emerged as a powerful tool that allowed in vivo quantification of physiologic processes including myocardial perfusion and metabolism, as well as neuronal and receptor function for more than 25 years. Now PET imaging has been playing an important role in the clinical evaluation of patients with known or suspected ischemic heart disease. This important clinical role is expected to grow with the availability of PET/CT scanner that allow a true integration of structure and function. The objective of this review is to provide an update on the current and future role of PET in clinical cardiology with a special eye on the great opportunities now offered by PET/CT.(Korean J Nucl Med 39(2):124-132, 2005)