Four kinds of bio-based polyurethanes bearing hydroxy groups in the pendants were synthesized by the poly-addition of D-mannitol- and D,L-erythritol-derived diols (1,2:5,6-di-O-isopropylidene-o-mannitol and 1,2-O-isopropylidene-D,L-erythritol) with hexamethylene diisocyanate and methyl (S)-2,6-diisocyanatohexanoate and the subsequent deprotection of the isopropylidene groups. They were hydrolyzed much more quickly than the corresponding protected polyurethanes at 50 degrees C and pH 7.0, although their hydrolytic degradation rate was lower than that of polyurethanes with saccharic and glucuronic lactone groups, which had been reported in our previous articles. The introduction of D-mannitol units to the polyetherpolyurethanes containing poly(oxytetramethylene) glycol units also enhanced their hydrolyzibility. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 976-985, 2011