Out of 93 blood samples from suspected cases of bovine tropical theileriosis in calves presented to Teaching Veterinary Clinical Complex and Department of Veterinary Pathology, C.V.Sc., OUAT, 83 (89%) were found positive and 10 (11%) cases were found negative for theileriosis on blood smear examination. This indicates that theileriosis is highly prevalent among calves in Odisha. Out of 83 positive cases, 81 (99%) samples were from crossbred jersey and 2 (1%) were from deshi calves. This indicates higher susceptibility of exotic blood to Bovine Tropical Theileriosis. Season wise distribution of cases showed that the disease was highly prevalent in rainy 40 (48%) followed by summer 27 (33%) and least in winter season 16(19%). Distribution of positive cases of theileriosis among different age groups revealed that the cases were more in older calves of 7-12 month age followed by 2-6 month old calves and least in calves 0-1 month of age. This might be due to passive immunity from mother to calf. Out of 83 positive cases, 71 (86%) were female and 12 (14%) were male calves. The data indicates majority cases were in female calves followed by male calves. In majority of cases, common clinical signs recorded were anorexia, pyrexia, enlarged prescapular and prefemoral lymph nodes, trembling while standing, pale conjuctival mucus membrane, haemoglobinuria, nasal discharge, coughing and grinding of teeth. cachexia, diarrhoea. The corneal opacity was due to local infiltration of white blood cells. In the present study, the haemoglobin percentage (Hb%), Packed cell volume percentage (PCV %) and Total erythrocyte count (TEC) (million/ cumm) were lower than the normal value in theileria positive animals. These were indication of anemic condition in affected animals. There was lowering of Total leucocyte count (TLC) (thousands/ cumm) in affected animals. Among erythrocyte indices, lowering in values of MCV (fl) and MCHC (%) were recorded in affected calves as compared to healthy calves. MCH (pg) values didn’t show any significant change in affected calves as compared to apparently healthy calves. In differential leucocyte count, the average percentage of neutrophil, eosinophils, lymphocyte and monocyte were within normal range was noticed for percentage of basophils in affected animals in comparison to apparently healthy animals. Serum biochemical studies revealed lowering in total protein and albumin value in affected calves as compared to healthy calves where as non-significant difference was noticed for globulin value, hypoglycemic condition in theileriosis affected calves where as non-significant difference noticed for urea value.