A new biosorbent, methylated yeast (MeYE), was prepared for the adsorptive separation of proteins from aqueous solutions. Yeast was methylated in a 0.1 M HCl methyl alcohol solution at room temperature. About 80% of the carboxylic groups of yeast could be methylated within 9 h. The adsorption of egg albumin to MeYE was studied to evaluate the protein adsorption ability of MeYE. At near neutral pH, egg albumin was scarcely adsorbed to unmethylated yeast and the adsorption amount of egg albumin increased with increasing the methylation degree. The adsorption amount of egg albumin to MeYE increased with increasing pH from 4 to 7 and steeply decreased above pH 7. The Langmuir isotherm was applied to determine the apparent adsorption constant and the saturated adsorption amount of egg albumin to MeYE. Both the apparent adsorption constant and the saturated adsorption amount increased with the degree of methylation. The saturated adsorption amount of egg albumin to MeYE having methylation degree 77% was 8.41×10 -6 mol g -1 or 0.378 g g -1 at near neutral pH.