Abstract: A new chalating agent is used to accelerate excretion of radioactive nucleiPu, Th and U from animal body. The effect of the new medicine is better thanCa-DTPA. Results of acute and subacute toxicity tests on mice, dog and monkey,and a series of pharmaceutical tests showed that the toxicity of the new medicineis not larger than Ca-DTPA. The new chelating agent labelled by ~3H and ~(14)C isused for the study on the absorption, distribution, metabolism and excretion ofmice. ~(14)C-H-73-10(n) is composed of ~(14)C-formal tetraethylene pentamine and1,2-dihydroxybenzene-3, 5-disulphonic acid salt. Specific activity of the productis 1.02μCi/mg. Its radiochemical yield is over 4.3%. ~3H-H-73-10(n) is composedof ~3H-1,2-dihydroxybenzene-3, 5-disulphonic acid salt, tetraethylene pentamineand formal. Its specific activity is 9.8 μCi/mg and radiochemical yield over50%. ~3H-H-73-10(G) is prepared by electric-discharge method with a specificactivity of 55 μCi/mg.