Chlorpyriphos (CPF) is a broad-spectrum organophosphate pesticide which is widely used in agriculture and in domestic use against harmful insects. To our knowledge literature on chronic low dose effects of CPF especially on ultrastructural pathology are scanty. Therefore the present study aimed to investigate the effect of oral (p.o.) administration of CPF induced ultrastructural alterations in liver and kidney of indigenous chicken. The birds were divided into two groups I and II. Group I served as control and group II was treated with CPF (0.36 mg/kg) orally daily upto 12 weeks. Renal and hepatic tissues were collected at monthly interval up to 3 months and processed for ultrastructural pathology. Ultrastructural examinations of liver and kidney indicated significant injury in chicken receiving chronic dose of chlorpyriphos. The results indicated that chronic CPF intoxication has a toxic effect on liver and kidney.
