This study was carried out to ascertain the changes in hematology and serum constituents in cross bred cattle affected with bovine theileriosis in semi arid zone of Pakistan. A total of 50 cross bred cows of age 2-5 years were included in the study. Twenty animals of same age were kept as healthy controls. The affected animals showed signs and symptoms of bovine theileriosis i.e., high rise in body temperature, general debility, enlarged prescapular lymph nodes, mucosal hemorrhages, conjunctivitis, etc. These animals were subjected to examination of peripheral blood smears for the presence of Theileria annulata schizonts in infected mononuclear cells and piroplasms in red blood cells. Significant (P≤0.05) decrease was observed in total erythrocyte counts, packed cell volume, hemoglobin, serum total proteins, albumin, globulins, glucose, calcium, phosphorus, cholesterol and triglycerides concentrations in cattle affected with bovine theileriosis compared with healthy controls, while significant (P≤0.05) increase was observed in serum bilirubin and alanine transaminase of affected cattle compared with healthy controls. Non significant differences were observed in serum magnesium and uric acid concentration in both affected and healthy controls. These observations revealed that bovine theileriosis caused by T. annulata in cross bred cattle in semi arid zone is associated with hemato-biochemical alterations.