A method is described for the isolation of 2S, 7S and 11S proteins of soybean. The unfractionated proteins are first precipitated with Mg (11) which yields a 11S-rich precipitate and this is further purified by (NH4)2SO4 precipitation. From Mg(11) supernatant which is rich in 7S and 2S proteins, they are separated by the use of (NH4)2SO4 and cold ethanol. The 7S and 11S protein are obtained in a highly purified form as indicated by ultracentrifugation and polyacrylamide gel electrophoresis.