In this work the horses were subjected to submaximal exercise for 20 minutes anc! physical mu! electrocardiographic examinations were carried out before and after exercise. It has been fund that after exercise respiratory and pulse rate increased while, all time intervals and durations were abbreviated cuu! decreased post-exercise. Heart rate reaching more than doable the resting values with spiking of the T waves. These changes were returned within 8 minutes of rest to the normal.