Abstract: STUDY ON THE LABELING CONDITION OF 188ReAEDP ANDTHE BIODISTRIBUTION IN RATSZhang Yadong\ Lu Jie\ Lü Gongxu(Department of Chemistry, Beijing Normal University, Beijing 100875)ABSTRACTLabeling of 1aminoethylene diphosphonate acid(AEDP) with 188Re is studied by a direct labeling method in the presence of SnCl2·2H2O as reducing agent. The effects of mass of AEDP, glucose, ascorbic acid，pH value and the concentration of SnCl2·2H2O on labeling efficiency are investigated. The optimum labeling condition is determined. The results show that the labeling yield is more than 90%, the radiochemistry purity of 188ReAEDP is more than 90% and can remain for more than 5 h.The biodistribution in rats shows that the proportion of muscles and bone to blood reach the peak value within three hours and remain high value within twentyfour hours. The clear of drug from blood is fast. So 188ReAEDP is perhaps a potential palliation therapeutic agent and the further study is worthwhile.Key words biodistribution in rats 188ReAEDP labeling condition