The length and termination of the right coronary artery of the human heart were studied in 81 hearts, after injection of a colored substance containing a radiopaque medium. The hearts were radiographed, dissected, drawn and photographed. The long type of right coronary artery, defined as a branch that reached or ran distal to the crux cordis, was found to be much more frequent (88.8%) than the short type and terminated in the majority of the cases (71.6%) as one of the posterior branches of the left ventricle. The relationship between these findings and the so-called "coronary circulation dominance" is discussed.