Анотация: Five clinically healthy Sella Italiana horses were used in order to assess the haematological response to different workload. Blood samples were collected on each horse at rest, immediately after the exercise and 30 min after the end of the exercise. An automated haematology analyzer was used to assess red blood cells counts, haemoglobin concentration, haematocrit (Hct) and white blood cells counts One-way for repeated measures analysis of variance (ANOVA) was used to determine the statistical differences and it showed a significant effect of the exercise on sand track on Hct. Our results confirm that exercise has variable effects on the studied parameters depending on work intensity. Based on our results it is possible to affirm that the indices studied could be useful in the assessment of the fitness of sport horses and aerobic working capacity, correlated to blood fluidity