A new galactose-specific lectin (MPL) from Musca domestic pupae was isolated. The purification procedure entailed extraction with aqueous buffer, GRBC (glutaraldehydeized red blood cells) adsorption, affinity chromatography on Sepharose-4B and gel-filtration on SephadexG-200. By SDS-PAGE, purified MPL yielded three bands, with a total molecular mass of 84 ku. By gel-filtration, the molecular mass of MPL was determined to be 86 ku. MPL exhibits high affinity towards D-galactose. The hemagglutination activity of MPL was independent of Ca²⁺, heat liable and stable in the range of pH 6～9. Antibacterial activity of MPL has been observed against Escherichia coli, Bacillus subtilis and Salmonella typhi.