In this study, M-Mode and 2-D echocardiographic analysis was performed to investigate the heart structure of 90 English breed horses used for different purposes. The horses were divided into 3 groups: racing horses (Group I), untrained horses (Group II) and show-jumping horses (Group III). M-Mode sections in the fourth right intercostal space were taken from the musculus papillaris, chordae tendinei, mitral valves and aortic root using 2-D, and the measurements were made in four standard transudcer positions. The movement of the left ventrical. right ventrical, left atrium, aortic root, interventricular septum, left ventricular posterior wall and heart walls were analysed, and the pumping capacity of the left ventrical was determined. The end-systolic and end-diastolic diameters were measured and the data were compared between the groups.