A novel combined process comprising microfltration (MF) and subsequent high pressure processing (HPP) was investi- gated. Skimmed colostrum contaminated with various bacteria species was subjected to cross-␣ow MF at pore sizes of 1.4 and 0.8 mm. The MF permeates contained a residual microbial burden that was reduced to undetectable levels by HPP at 400 and 500 MPa for 10 min. Native IgG was reduced to 36e73% (MF ␣ 400 MPa HPP) and 19e30% (MF ␣ 500 MPa HPP) of the original content. In direct application to contaminated colostrum, HPP was shown to be less detrimental to IgG than heat treatment at conditions giving similar microbial reduction ef␣cacy.