The normally developing cardiovascular system of the chicken resembles that of the human. The purpose of the present study is to investigate some macroscopic and microscopic similarities between the chick and the human heart. For this study 20 adult and 10 newborn Broiler chickens were used. The heart and great vessels were routinely fixed in 10% formaldehyde in a phosphate buffer. Five adult and five newborn chicks hearts were embedded in paraffin. All section were examined by light microscopy. The atrioventricular valve of 15 adult chick hearts were examined macroscopically. While some structures previously reported were determined, two different properties of the mural leaf which are chordae tendineae in its posterolateral region anchoring at the right ventricle and its widening from the anterior to posterior commissure was also observed.