Background: The sinoatrial node (SAN) and atrioventricular node (AVN) blood supply is highly variable and recording of anatomic variations of the arteries supplying blood to the SA node and AN node will help to prevent potential complications following cardiac ablation procedures or in valvular surgeries. The objectives of the study is to study the arterial supply of the conduction system and its relation with the dominance of coronary artery and to find the origins of the major atrial arteries in patients undergoing coronary angiography. Methods: The study included 300 consecutive patients (196 females and 104 males) admitted for diagnostic coronary angiography at madras medical college, chennai. Coronary angiography was done in a routine manner without any special views for visualizing atrial arteries. The origins of sinoatrial and atrioventricular nodal arteries and its relation with dominance of artery were recorded. Results: Right coronary Artery (RCA) is dominant in 77.20%, Left coronary artery (LCA) is dominant in 18.43% of patients and Co–dominant in 4.37% of the patients. The SA nodal artery arises from the RCA in 57.20% of the patients, by the circumflex branch of LCA in 40.14% and by both coronary arteries in 2.66% of patients. The AV nodal artery like SA nodal artery arises commonly arises from the RCA (78.22%) than by the Cx branch of the LCA (18.66%). Conclusions: The data from our study may help the cardiologists, cardiac surgeons and electrophysiologists in their day to day practice.