<p>Bovine theileriosis is a common tick-borne disease leading to reduced productivity, significant mortality and huge economic loss. The present study was conducted at Regional Clinical Laboratory, District Veterinary Centre, Kannur, Kerala, India to evaluate the haemato-biochemical parameters in bovine theileriosis caused by <i>Theileria orientalis</i>. The whole blood and serum samples of 75 cows collected from different parts of Kannur district, Kerala India, tested positive for <i>T. orientalis</i> by light microscopy and polymerase chain reaction were subjected to a battery of haemato-biochemical tests such as complete blood count, serum ionized calcium (iCa), magnesium (Mg), inorganic phosphorus (P), sodium (Na), potassium (K), chloride (Cl), copper (Cu), zinc (Zn), iron (Fe), total iron binding capacity (TIBC), total protein (TP), albumin, gamma-glutamyl transferase (GGT) and aspartate aminotransferase (AST). The pattern of variation in each parameter was evaluated retrospectively by grouping the animals based on the chronicity of infection into chronic and acute cases, and re-grouping them based on parasitemia rates. The variation of each hemato-biochemical parameter between groups in both the distribution patterns were compared and studied. Variations in haematological parameters such as haemoglobin, packed cell volume and red cell distribution width revealed a weak correlation with parasitemia rates. However, the between-group variations in biochemical parameters like GGT, TP, albumin, zinc, copper and TIBC were more consistent in the distribution based on chronicity of infection pointing towards the existence of hepatic impairment and trace mineral imbalance specifically in cows persistently infected with theileriosis.</p>