In 51 (1.2%) of 4,250 patients studied by selective coronary arteriography, one or more major elements of the coronary arterial system originated from the sinuses of Valsalva in an ectopic manner. The majority of variations involved the left coronary artery. The majority of ectopic ostia were located in the right sinus of Valsalva. Failure to recognize variations in coronary arterial origin can prolong arteriography procedures and lead to errors in interpretation of coronary artery anatomy and pathology. It is concluded from this experience that the incidence and location of major variations in coronary arterial origin are relatively predictable. The data are useful in expeding coronary arteriography procedures and thus improving patient care.