The present work was conducted on 25 hearts of healthy donkeys of both sexes. Three methods were adopted to clarify the musculature of the ventricles; nitric acid method, acetic acid method and flour paste method. The ventricular myocardium was arranged into three layers: superficial, middle and deep. The superficial layer consists of eleven bundles arranged longitudinally from the base to the apex of the heart. Moreover, a thin subepicardial layer separated it from the epicardium. The middle layer on the right ventricle was horizontally oriented, while on the left ventricle it was represented by three bands; (A), (B) and (C). The deep layer on the right ventricle was formed of two bands (A) and (B) while on the left ventricle consisted of a single band (C), in addition to some fibers derived from the superficial layer. The
intervrentricular septum was formed from fibers extended from the middle and deep layers. The papillary muscles were four in the right ventricle and two in the left one.