The effect of processing conditions on the protein nutritive value, the methionine and available lysine content, and the antitryptic activity of two types of isolated soybean protein and of intermediate fractions obtained during protein isolation procedure was investigated. Protein efficiency ratios (PER) of the extraction mixture, of the filtered extract, and of the isolated proteins were inferior to those of the original meal. PER of isoelectrically precipitated protein and of calcium salt coagulated protein were practically identical. PER of spray-dried isoelectric proteins was significantly higher than that of the same proteins when freeze-dried. Toasting of the spray-dried proteins did not improve their nutritive value. PER of isolates from unheated and from toasted meal showed identical values.