Colibacillosis occurs as an acute fatal septicaemic disease of young buffalo calves and is seen worldwide. The main determinant of the disease is decreased immune status of the young one along with improper managemental conditions and stress factors, which also enhanced the growth of opportunistic bacteria and therefore infection flares up. Colisepticemic form of colibacillosis usually results in the rapid death of the calf and is associated with an E. coli bacteraemia. Present paper highlighted the incidence and pathology of colibacillosis on lungs of buffalo calves. Incidence of colibacillosis affecting lung was recorded as 20.73 per cent. Grossly, the affected lungs showed moderate to marked areas of congestion, haemorrhages and presence of white necrotic foci on parenchyma. Microscopically, lung sections showed marked vascular congestion along with hyperplasia of bronchiolar epithelium, moderate to marked haemorrhages in between alveoli, marked cellular infiltration of neutrophils, macrophages and few lymphocytes in lung parenchyma, perivascular and peribronchiolar cellular infiltration, pulmonary emphysema and thickening of alveolar septa due to congestion of septal blood vessels and leucocytic infiltration along with presence of oedema in some alveoli. 1357106867.php