Abstract: A new peptide ligand containing adenine 9-N-(S-tritylmercaptoacetyl) diglycylaminoethyl adenine (Tr-MAG2-Ade) is synthesized and characterized by IR, 1H NMR, 13C NMR, MS and elemental analysis. The complex 99Tcm-MAG2-Ade is prepared by directly labeling method. The partition coefficient and stability in vitro indicated that the complex is hydrophilic and stable over a period of 6 h at room temperature. The biodistribution of 99Tcm-MAG2-Ade in mice bearing S180 tumor shows that a tumor-specific accumulation and quick blood clearance. The uptake ratios of tumor to muscle and blood at 3 hours post injection are 5.70 and 1.55, respectively. The complex 99Tcm-MAG2-Ade appears to be a potential tumor imaging agent.