Abstract: The complex 99 Tc mN DMSA (DMSA:Dimercaptosuccinic acid) is synthesized through ligand exchange reaction.The two step procedure involves the initial reaction of 99 Tc mO 4 -with succinic dihydrazide(SDH) as a donor of nitride nitrogen atom (N 3- ) in the presence of stannous chloride dihydrate as reductive agent and propylenediamine tetraacetic acid(PDTA) as complexant,followed by addition of the DMSA ligand.The radiochemical purity (RCP) of the product is over 90% measured by thin layer chromatography (TLC).The conditions of preparation for the 99 Tc mN DMSA complex are optimized .The stability and the partition coefficient of the 99 Tc mN DMSA complex are studied.It is stable over 6 h at room temperature.Its partition coefficient(lg P =-3.74) indicates it is a good hydrophilic complex.The biodistribution results in mice indicate that the 99 Tc mN DMSA complex is accumulated in bone with high uptake and good retention and less kidney uptake,suggesting it will be potentially useful as the first bone imaging agent containing the 99 Tc mN 2+ core.The biodistribution comparison in mice of the 99 Tc mN DMSA complex with the 99 Tc m DMSA complex indicates that the presence of the 99 Tc m nitrido group significantly alters the biological properties of the 99 Tc m complex.