Objective To explore the method of radiolabeling anti-Aspergillus monoclonal antibody (WF-AF-1)with 99mTc,and evaluate the in vitro and in vivo characteristics of 99mTc labeled WF-AF-1 (99mTc-WF-AF-1). Methods 99mTc-WF-AF-1 was prepared with indirect-labeling method.The labeled product was identified using thin layer chromatography.Suspensions of Aspergillus fumigatus,Staphylococcus aureus and Candida albicans were incubated with 99mTc-WF-AF-1 to evaluate the specificity of the labeled antibody.Mice were injected with 3.7MBq of labeled product.The biodistribution was measured at 40min,2h,4h and 7h after injection. Results The labeling efficiency of 99mTc-WF-AF-1 was over 95%,and the labeled product was stable in serum and phosphate buffer solution.In vitro binding of 99mTc-WF-AF-1 revealed that the labeled Mab-WF-AF-1 preferentially binds to Aspergillus fumigatus. Biodistrbution data showed that the labeled antibody was deposited mainly in liver,kidneys and spleen.The radioactivity uptake in blood at 40min and 7h was (2.51±0.23)%ID/g and (0.53±0.13)%ID/g,respectively. Conclusions The labeling efficiency and stability of 99mTc-WF-AF-1 are high.The labeled antibody is excreted mainly through the liver and kidneys with fast clearance in blood in normal mice.