Effect of Chlorpyrifos an organophosphate insecticide on the glycogen and protein in liver and kidney of Gambusia affinis exhibited notable alterations. Liver and Kidney being the main site of metabolic activity in body and highly active in both toxifying and detoxifying insecticides, was selected for the study purpose. Sublethal dose for 96-hrs 0.028 ppm of chlorpyrifos was calculated by probit method. The minimum effective dose 10%, 20% and 30% was given to the fish for 15 days. Chlorpyrifos insecticide caused significant decrease in glycogen and protein contents in the liver and kidney of treated fish. This depletion is due to depression of glucokinase activity resulting in the reduction of glucose 6-phosphate. The reduction in protein content may be due to increased utilization of protein to meet out the energy demand when the fish is under stress condition. This may be related to regressive phenomenon with in the cells. It was observed that Chlorpyrifos disturb the chemical constituents of the fish which leads to cell damages and finally mortality of fish.