A new hydrophilic copolymer containing a-hydroxy allyl alcohol segments was prepared by reducing poly(alpha-hydroxyacrylic acid) (PHA) with NaBH4 in water and mixed solvents of methanol and polar solvents. Conversion to the desired allyl alcohol group in the resultant polymers was confirmed with ICP, FTIR, and C-13 NMR spectroscopies. The degree of conversion was as law as 5% for PHA. reduced in aqueous solution, while for those reduced in the mixed solvents it was significant (ca. 60-70%).