The use of PET in cardiology centers primarily around the qualitative and quantitative visualizations of cardiac perfusion with 13N labeled ammonia or Rubidium. Second is the study of anaerobic metabolism with 18F-fluorodeoxyglucose or of the myocardial innervation can be revealed by 11C or 11F labeled pre- and postsynaptic neuronal ligands. Data obtained by PET compare favorably with pictures obtained with thallium or Tc-MIBI scans. Quantification is only possible with PET. The latter is indispensable for evaluation of therapeutic success after revascularisation and the assessment of cardiac transplants. Imaging of metabolism by FDG seems superior to other methods for localization of chronic myocardial ischemia. It is used for the study of revascularisation success after acute myocardial infarction. Studies have been published recently on the assessment of cardiomyopathies and of myocardial function in valvular heart disease using fatty acids and acetate. Information on regional myocardial function not obtainable by other methods can thus be measured. The interesting possibility to investigate drug activities and dose optimization by neuronal ligand binding is as yet not ready for clinical use. A short review of relevant clinical data is presented.