Starting with properly protected sugar alcohols, bioerodible polycarbonates having pendant hydroxy substituents at the main polymer chain (poly(hydroxyalkylene carbonate)s, (PHAC’s)) have been synthesized for the first time. The PHAC’s are the first examples of water-soluble polycarbonates. Due to water solubility, these polyols may replace PEG’s in some applications. On derivatization of the hydroxy groups as a carboxylic or carbonic acid ester or as an ortho ester, additional bioerodible polycarbonates having quite different solubility and degradation properties were available.