Polyaddition of saccharic acid dilactones prepared from D-glucose and n-mannitol, D-glucaro-, and D-mannaro-1,4:6,3-dilactones (1 and 2, respectively), with hexamethylene diisocyanate (3a) and methyl (S)-2,6-diisocyanatocaproate (3b) was carried out by using dibutyltin dilaurate as a catalyst at 50, 25, and 0 degrees C to give polyurethanes (4 and 5) having dilactone moieties in the main chains. The resulting polymers were found to decompose easily in phosphate buffers under neutral or slightly basic conditions (pH 7 or 8). Therefore, the polyurethanes may be used as novel degradable polymeric materials.