Chlorpyriphos (CPF; diethyl 3, 5, 6-trichloro-2-pyridyl phosphorothionate) an organophosphate is one of the most widely used insecticides in agriculture worldwide. It has also been used for the control of termites in chicken houses.The objective of the present work was to assess the effect of oral (p.o.) administration of CPF in indigenous chicken. The birds were divided into two major groups -Group I and Group II Group I served as control and Group II was treated with CPF (0.36 mg/kg) orally daily up to 12 weeks. Detailed post mortem examinations of the weekly sacrificed birds were conducted and representative tissues were collected for histopathological examination. Histopathologically, liver tissue of CPF intoxicated chickens showed degeneration, hepatocellular necrosis, congestion, haemorrhages, dilatation of sinusoids and mononuclear cell infiltration. The kidneys showed haemorrhages, cellular swelling, dilatation of Bowman’s space and focal coagulative necrosis. Brain showed satellitosis, neuronophagia and degeneration of Purkinje cells. Degenerative changes along with congestion and haemorrhage were observed in intestine, brain and heart. The results indicated that chronic CPF toxicity produces histopathological alterations of different organs in the treated birds.