Wistar rats (male) were divided into 3 groups — group A (GA) served as control, group B (GB) were daily administered chlorpyrifos (Anu Products Ltd., India) orally at a dose of 5 mg/kg b wt. and animals in group C (GC) received daily an oral administration of chlorpyrifos at a dose of 10 mg/kg b wt. Rats were sacrificed on 1st, 2nd, 4th, 6th and 8th week after initiation of the experiment. Kidneys were extirpated and fixed in aqueous Bouin’s solution. The tissues thus fixed were routinely processed for histological studies. The present study showed that the histopathological changes were caused in kidney of rats by chlorpyrifos administration. The changes noticed were mainly the shrinkage of glomerulus at initial stage of treatment, the tubular dilation, the glomerular hypercel...