Abnormalities of the coronary arterial circulation represent a broad spectrum of anomalies. Some of these coronary arterial anomalies are of little clinical significance and are generally discovered either as incidental findings at autopsy or at the time of diagnostic coronary angiography in patients with atherosclerotic ischaemic cardiac disease. Some of these coronary arterial anomalies, however, are associated with a markedly abnormal natural history that may include significant cardiac morbidity very early in infancy, or increased risk of cardiac sudden death in childhood or adolescence. It is therefore important that we have a system for the naming and classification of these anomalies, to stratify them according to the associated risk and to develop rational approaches to evaluation and management. To apply any system of nomenclature reliably and responsibly, it is essential that each term be associated with a definition that is known and accepted by users of terminology. Such definitions are included in the specifications of both the Society of Thoracic Surgeons Congenital Heart Surgery Database and the European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Database. These databases use the Diagnostic Short List of the version of the International Paediatric and Congenital Cardiac Code derived from the nomenclature of the International Congenital Heart Surgery Nomenclature and Database Project of the European Association for Cardio-Thoracic Surgery and the Society of Thoracic Surgeons. This article will provide the nomenclature and definitions used by these databases for anomalies of the coronary arteries.