Proficiency in the anatomy of coronary arteries and their variations is significant for proper interpretation of the coronary angiographies, assessment of the complexity and result of the coronary insufficiency as well as surgical myocardium revascularization. The objective of this study is anatomy-radiology research of the methods of branching the main trunk of left coronary artery and to prove importance of the diagonal branch (ramus diagonalis) existence in the conditions of coronary insufficiency. In this study we have analyzed 100 coronary angiographies done at the Clinic for Heart Diseases and Rheumatism of the Clinic Center of University of Sarajevo and dissected 20 human hearts from the Institute of Anatomy. In our study we have com...