Objective To investigate the imaging and biodistribution of 99Tcm labeled peptide ( phage-SHSWHWLPNLRHYAS) high-binding VEGF receptor 3 in nude mice with ovarian cancer. Methods We used NHS-MAG3 as the bifunctional chelating agent and synthesized the peptide above. It was completed with pre-stannous direct labeling by 99Tcm and then the labeling efficiency was determined by paper chromatography. The tumor bearing mice were injected via tail veins with radiolabeled peptide. The tumors were imaged with single photon emission computed tomography ( SPECT) . We measured and calculated the biodistribution of the radiolabeled peptide. Results The labeled rate was 95. 27% and the radiochemical purity was 96% . Under a SPECT apparatus,we observed tumor location image at 1 h post injection and the tumor images was the clearest at 3 h post injection,with the injected dose per gram of tissue ( % ID/g) of ( 30. 20 ? 6. 89) at the tumor sites. The tumor/muscle ratio was 13. 13. Conclusion Our peptide can accumulate in the tumor masses. It is hopeful to be used as an ovarian cancer targeting vector for diagnosis and therapy of the cancer.