On 12th randomized specimens of the human heart, of either sex, from 19-84 years of age, I investigated the vascularization of the conducting system of the heart in relation to the type of coronary ramification, by the dissection and injection-corrosive method. The symmetrical type of arterial vascularization was established in 47.5%, the right type in 45% and the left type in 7.5% of the cases investigated. Most often the right anterior sinus nodal artery was in the symmetrical type and the left anterior sinus nodal artery in the right type of arterial supply. The right atrioventricular nodal artery was in 90% of the hearts in the right and symmetrical type of the arterial vascularization.