Ultrasonographic features of the heart of lactating dairy water buffaloes were described and the relationship between the echocardiographic features and milk production performance was established in this study. Fifty-six, 3-11 year-old Bulgarian Murrah and Philippine carabao x Bulgarian Murrah water buffaloes, weighing 300-450 kg, with milk production of 0.9-9.8 kg/day were examined to determine the B and M-mode ultrasonographic features of the heart. The lactating animals were grouped into high (>5.5 kg, 35 animals) and low (≤5.5 kg, 21 animals) average daily milk yield and were further classifed based on state of pregnancy (24) and non-pregnancy (32). An ultrasound machine equipped with a 3.5 MHz convex scanner was used to evaluate the heart. Two-dimensional ultrasonography (B-mode) was used to identify and describe the cardiac structures while M-mode echocardiography was used to measure the cardiac structures. The diameter of the aorta of high milk producing water buffaloes was greater than in low milk producing ones. In high milk producing buffaloes, non-pregnant animals had higher left ventricular internal diameter at diastole, left ventricular diastolic volume and stroke volume than pregnant ones. The echocardiographic values obtained in the study can be useful in evaluating cardiovascular disorders of dairy water buffaloes with varying milk yield.