An a-amino acid./V-carboxy anhydride polymerizes into poly-a-amino acid, which is a model substance of protein. The synthesis of/3-hydroxyl-containing poly-a-amino acids is of interest, because the polymers provide models of water-soluble proteins. Polymers containing protected ß-hydroxyl groups, viz., poly-0-acetyl-DL-serine, poly-O-acetyl-L-serine, 2'33 and poly-0-acetyl-L-threonine, 35 have been prepared by the polymerization of the ...