Present research embodied effect of organotin tributyltin chloride on freshwater prawn, Macrobrachium kistnensis. In toxicity evaluation of organotin tributyltin chloride on Macrobrachium kistnensis is highly sensitive to TBTCl toxicity. In the present study the safe concentration was 0.0322 ppm. The respiratory changes in oxygen consumption in the prawn, Macrobrachium kistnensis after exposed to 48hours, 1/3rd and 1/10th lethal and sublethal concentrations for 2, 4, 8, 12 and 24 hours have also been studied. The death of freshwater prawn, Macrobrachium kistnensis might be due to the impact of TBTCl on gill which ruptured the gill lamellae resulting decline in respiratory rate, an inhibition of the electron-transport system (ETS) or an effect on mitochondrial integrity. From these observation it can be inferred that the organotin compound disrupting enzyme-mediated process and / or disrupting cellular structures. From this it can be conclude that the TBTCl is very toxic to the freshwater prawn, Macrobrachium kistnensis. Therefore, the release of organotin compounds in aquatic environment especially in freshwater ecosystem should be controlled.