Detailed information on the roentgenographic anatomy of congenital coronary arterial variations was evolved by an extensive study of the pertinent literature and a series of 231 patients, a large number of whom were studied by various roentgenographic procedures. Basic categorization was made according to their pathophysiology: minor primary variations; major primary variations; and secondary variations. The various anomalies are discussed in detail, especially with regard to characteristics pertinent to roentgenographic diagnosis, and are illustrated, when possible, with contrast medium studies.