Cadmium is unique among non-essential metals in several of its toxicological effects because of its long biological half life, slow excretion and delayed action on the kidneys. Although cadmium poisoning in humans is uncommon, there are reports of chronic cadmium poisoning in workmen and also in others in certain polluted areas. At present there are no suitable methods either to measure the body burden of cadmium or to treat cadmium poisoning. The therapeutic effects of various chelating agents including 2,3-dimercaptopropanol (BAL) and its soluble glycosides have been studied without much success in acute cadmium intoxication. However, those studies were done before anything was known of the specific binding of cadmium to metallothionein, an intracellular low molecular weight protein. The potential role of this protein in the detoxification and toxicity of metals has been reviewed recently. The induced synthesis of metallothionein has a marked effect on the pharmacokinetics of cadmium and other divalent metals. Thus it is important to consider the intracellular binding of cadmium with metallothionein in developing a suitable chelation therapy for chronic exposure to cadmium. The in vivo chelation of cadmium with BAL or BAL and diethylenetriamine pentaacetic acid (DTPA) from rats exposed to cadmium is reported here.