Abstract The aim of this study was to investigate the morphometry of branching patterns of the main trunk of the left coronary artery (MT of LCA) in nonhuman primates, and comment on the current nomenclature. The biometric study was performed using stereomicroscopic dissection of hearts of healthy and fertile nonhuman primates (Cercopithecus aethiops sabaeus) of both sexes. Our results reveal that the MT of LCA terminates in a bifurcation into the anterior interventricular branch (AIB) and the circumflex branch (CB) (74.6%), trifurcation into the AIB, CB, and diagonal branch (DB) (23.6%), or occasionally quadrifurcation into the AIB, CB, and two DBs (1.8%). This is similar to the case in humans. Furthermore, two morphological aspects of the DB spatial distribution, in addition to its branching pattern, resemble the DB in humans. Myocardial bridges observed over the DB in the Cercopithecus aethiops heart further contribute to the similarity with humans. The resemblance of the DB and its branches to their human counterparts make them a suitable model for experimental study on coronary circulation. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.