A total of 112 male albino rats (Rattus norvegicus) were divided into seven groups and exposed to lead acetate trihydrate (0, 0.125, 0.25, 0.5, 1.0, 2.0 and 4 per cent for 1 to 8 months) in drinking water to investigate possible histochemical changes of nine renal dehydrogenases due to lead intoxication. A marked increase in the activity of lactate-, glucose-6-phosphate-, α-glycerophosphate-, reduced nicotinamide adenine dinucleotide (NAD)- and reduced nicotinamide adenine dinucleotide phosphate (NADP) dehydrogenase was observed while significant reduction was recorded in the activity of succinate-, malate-, isocitrate- and glutamate dehydrogenase. Changes in the activity of renal dehydrogenases were seen mainly in the pars recta and to a lesser extent in the pars convoluta and the ascending thick segment of the loop of Henle while the other medullary portions of the renal tubule were less affected. These histochemical findings led us to conclude that such changes in the renal dehydrogenases activities were due to chronic lead exposure and could be an adaptation to the metabolic, structural and functional alterations in the organelles of the renal cells especially the mitochondria.