the heart of the ostrich (struthio camelus), just like the domestic birds's heart, has a muscular right atrioventricular valve without chordae tendinae and a membranous left atrioventricular valve with chordae tendinae than extends between the cusps and 3 papillary muscles.the aim of the study was to describe the papillary muscles, number, position and some morphologic characteristics. fifty ostrich hearts (struthio camelus), were dissected and fixed in 10 % formalin and which got histological slices from 7 microns themselves they were stained with van gieson and h e. the macroscopic study evidenced absence of papillary muscles in the right ventricle and in the left ventricle 3 muscular masses formed by longitudinal trabeculae carneae that give insertion to the chordae tendinae. it was observed in the histological slices that the dorsal and ventral insertion points of the right atrioventricular valve to the ventricular wall, are prolongations of the muscle that forms the valve and shows conductive cardiac fibers. in the left ventricle, the longitudinal trabeculae carneae also show conductive cardiac fibers the ones that extend to the zone of insertion of the chordae tendinae. the results evidence that the heart of the ostrich (struthio camelus) does not have papillary muscles of conical form like in the human heart, are more developed muscular formations than in the domestic birds's heart and functionally acts like papillary muscles to show conductive cardiac fibers.