Abstract: After a single intragastric gavage to mice and rats, the LD₅₀ of 2,3-dimercaptosuccinic acid (DMSA) were found to be 6 and 4g/kg, respectively.Dogs were given intragastrically DMSA 0.5 g/kg daily (5 days/week) for 6 weeks. Vomiting occurred and food intake decreased, thus causing a loss of body weight. However, no remarkable changes were found in blood picture, blood glucose, electrocardiogram, liver function tests (BSP, serum alkaline phosphatase, thymol turbidity and SGPT) and renal function tests (NPN and creatinine). Autopsy revealed a slight congestion in the duodenum. A daily dose of 0.2 g/kg caused no pathological signs.In rabbits given an intragastric gavage of DMSA, the blood SH content rose to a peak at 1/2 hour, and then declined in 5 hours.In mice given a subcutaneous injection of lead acetate (²¹⁰PbAc₂) the bone and kidney contained more ²¹⁰pb than other organs. Both DMSA and sodium dimercaptosuccinate (Na-DMS) could diminish the ²¹⁰pb contents in tissues and promote the urinary excretion of ²¹⁰pb.In rabbits given a subcutaneous injection of CuSO₄ an intragastric garage of DMSA hastened the urinary excretion of copper markedly. Both sodium bicarbonate and sodium citrate enhanced the effect of DMSA.Mice were given an intramuscular injection of K-¹²⁵Sb-tartrate, ⁹⁰Sr (NO₃)₂, ²⁰⁴Tl₂SO₄ or ¹⁴⁷Pm(NO₃)₃, followed immediately by an intragastric gavage of DMSA and NaHCO₃. There appeared a striking increase of metal excretion into the urine, amounted to about 6 times for ¹²⁵Sb, 2 times for ⁹⁰Sr, 11 times for ²⁰⁴Tl and 12 times for ¹⁴⁷pm as compared to the control mice. The radioactivities in blood and tissues decreased.These results indicate the benefits of DMSA per os in the treatment of intoxications by certain metallic compounds. DMSA is very stable and may be administered orally with little toxicity. Further studies on DMSA is warranted.