The present work conducted on 25 clinically diseased friesian calves. Ten healthy calves wer used as control. The age of animals ranged between 6-8 months. Diseased animals manifested inappetence and emaciated and anaemic. Some cases showed high fever and haemoglobinuria, while others showed prominent enlargement of the external lymph nodes. Laboratory examination of the blood smears revealed that diseased animals were suffering from piroplasmosis. The haemogram of the diseased calves showed decreae in the total red cells count, per mm3, haemoglobin content and packed cells volume. In the diseased calves, there was significant leucopenia associated with a drop in the absolute values of neutrophils, eosinophils and lymphocytes. On the other hand, marked increasse was reported in the basophils and monocytes. Increased activity of blood serum transaminases and lactic dehydrogenase was noticed in the diseased calves. Meanwhile, marked elevations in blood serum total bilirubin and globulin were noticed with a decrease in total protein and albumin.