Fractional profile of proteins from baker's, brewer's, and alcoholic yeasts was studied, applying a consecutive treatment of commercial biomasses, with solutions with a gradient of ionic strength and pH. It was found that a large part (35-50%) of total proteins from investigated biomasses is extracted by means of 0.01 M KCl, pH 7.0, which together with proteins extracted by means of 0.65 M KCl, pH 9.5, makes the part of the easily extractible proteins (50-64% of the total protein amount). The remaining part of proteins is extracted by means of alkaline solutions only. The amino-acid composition of the isolated fractions indicated that they are suitable for usage as food product ingredients.