labelling of scorpion (mesobuthus tamulus concanesis pocock) venom was successfully achieved with tc 99m using direct tin reduction procedure. biodistribution studies were carried out in wistar rats at different time intervals after i.v. administration of the labelled venom. scintiimages were obtained after scorpion envenoming using a large field of view gamma camera to ascertain the pharmacological action of venom in the body. within 5 min of administration, labelled venom was found in the blood (27.7%), muscle (30.11%), bone (13.3%), kidneys (11.5%), liver (10.4%), and other organs. the level of venom in the kidneys was higher than in the liver. the labelled venom was excreted through renal and hepatobiliary pathways. an immunoreactivity study was carried out in rabbits after i.v. injection of labelled scorpion venom followed by the injection of the species specific antivenom. a threefold increase in uptake by the kidneys was observed compared with that seen with scorpion venom alone. the neutralisation of the venom in the kidneys was higher than in the liver.