Soybeans and soybean milk were subjected to a high-pressure treatment to examine resultant changes in the functional properties of the soy protein. The total solids and nitrogen contents of the treated soybean milk were found to be less than those of non-treated soybean milk. The trypsin inhibitor contained in soybeans proved highly resistant to pressurization, with half of the normal inhibitory activity remaining after a 30-minute treatment at 700 MPa. Lipoxigenase, which was more sensitive than the trypsin inhibitor, was rendered inactive by both a 30-minute treatment at 500 MPa and a 15-minute treatment at 600 MPa. Calcium and glucono-δ-lactone (GDL)-based gel formation and foaming, both functional properties of soy protein, were also tested. Compared to heat treatment, which activated many of the functional properties of soy protein, high-pressure treatment resulted in softer calcium and GDL gels and in reduced foaming.