Abstract: There has been no report about comparison of the abdominal aorta and renal artery in the neonate dog. So, it was decided to compare these two arteries in the neonate dog. Six normal neonate male dogs were studied. The specimens were processed in the routine way for electron microscopy. It was established that the only cell type found in the tunica intima was endothelium in both abdominal aorta and renal artery. In abdominal aorta, there were open connective tissue space, contains elastic fibers between the internal elastic membrane and the endothelium. In renal artery, endothelial cells attached directly to the internal elastic membrane and in some place, the internal elastic membrane interrupted for as much as a few microns. The only cell type was found in the abdominal aorta and renal artery tunica media was smooth muscle cells. There were more dense bodies in the renal artery smooth muscle cells than in the abdominal aorta. In the abdominal aorta tunica media, it was observed layers of smooth muscle cells alternate with elastic lamellae but in the renal artery, the smooth muscle cells were close to each other and a small quantity of collagen and elastic fibers were found between them. The adventitia of the abdominal aorta and renal artery was consisting of scattered fibroblasts among bundles of collagen and elastic fibers. Elastic fibers in tunica adventitia of renal artery were more than those in abdominal aorta.