The incidence of ectopic coronary ostia location was investigated in coronary angiograms of 5350 adult patients without associated congenital heart disease. Ectopic coronary origin from the right coronary sinus was observed more than twice as frequently than ectopias from the left coronary sinus. The most common variation (0.7% of all patients) was the origin of the left circumflex branch from the right coronary sinus. Praeoperative knowledge and angiographic demonstration of ectopic coronary arteries is essential in order to avoid damage of these vessels during prosthetic valvular surgery or by aortotomy, to achieve complete revascularization in bypass surgery, and to prevent complications during intraoperative coronary perfusion.