This study investigates the morphological and morphometric characteristics of the heart and major arteries in the common pheasant (Phasianus colchicus). Five adult male birds were used as samples. Various morphometric and histomorphometric parameters of the heart and its major arteries were measured. The detailed structure of the cardiac chambers was examined using scanning electron microscopy (SEM), and the expression patterns of desmin and ?-SMA proteins were evaluated through immunohistochemical staining. The heart exhibited an elongated, conical shape, with mean length and width of 2.94 ± 0.46 cm and 2.38 ± 0.15 cm, respectively. In the right ventricle, the basal and apical regions were thinner than the middle region (P<0.05). Overall, the thickness of both left and right ventricular walls decreased from base to apex. Although the wall thickness and luminal diameter of the left brachiocephalic trunk and left pulmonary artery were greater than their right counterparts, these differences were not statistically significant (P>0.05). In contrast, these parameters were significantly higher in the aorta and brachiocephalic trunks compared to the pulmonary arteries (P<0.05). The parietal wall of the right ventricle consisted of two distinct muscular layers. The thickness of the left ventricular wall in the middle and apical regions was approximately four and three times greater than that of the right ventricle, respectively. SEM observations revealed that the muscular right atrioventricular valve was connected to the free wall of the right ventricle by several muscular cords. The chordae tendineae of the left atrioventricular valve exhibited a branched appearance, with each chord composed of three to four thinner intertwined strands attached to a common papillary muscle. The Purkinje fiber network was extensively distributed throughout the myocardium, exhibited strong immunoreactivity for desmin, and was negative for ?-SMA. While the patterns of ventricular wall thickness, valve structure, and the extensive Purkinje fiber network reflect the functional differentiation of various cardiac regions and the adaptation of the heart and major arteries to the hemodynamic demands of birds, the unique structure of the muscular right atrioventricular valve adds subtlety to avian valvular diversity and highlights anatomical differences among bird species. Furthermore, the observed immunohistochemical differences, including positive desmin reactivity and negative ?-SMA expression in Purkinje fibers, indicate specialized structural mechanisms for rapid electrical conduction and coordinated ventricular contraction Keyword: common pheasant, avian, cardiovascular system, Immunohistochemistry