The coronary artery wall consists of three coats differently developed: tunica intima, tunica media, and tunica adventitia. The intima consists of a lining of endothelial cells, and a subendothelial layer. The intima is separated from the media by the internal elastic lamina, while the media consists of multiple layers of smooth muscle cells, collagen and elastic fibers. An external elastic lamina, considerably thinner than the internal elastic lamina and composed particularly of elastin, separates media from adventitia. Tunica adventitia consists of a significant amount of fibrous tissue, particularly collagen and elastic fibers oriented longitudinally. The current study aims to describe the histological structure of the coronary artery among different ages in Kirkuk governorate. Twenty hearts of twenty normal Iraqi adults, with age ranged from 40-70 years were taken from the forensic medicine department of Kirkuk Teaching Hospital in the Azadi region during the period from September 2021 to June 2022. Histological study showed that the inner diameter in left coronary artery was 3.4±0.5 mm and in right coronary artery was 2.9±0.6 mm. The tunica intima was made up of one layer of endothelial cells and was supported by the internal elastic lamina. Thickness of tunica intima of left coronary artery was 95.6±46.4 μm and of right coronary artery was 52.0±29.1 μm. The tunica media consisted of multiple layers of smooth muscle cells and connective tissues (elastic fibers, collagen and proteoglycans). Thickness of tunica media of left coronary artery was 129.8±49.4 μm and of right was 100.3±35.2 μm.