Degradation studies on a series of polyesterurethanes having different compositions of hard and soft blocks have been performed utilizing an accelerated test method. Degradation was followed by titrimetry, mass loss, mechanical properties and infrared spectroscopy. As the number of methylene groups present within the polyester moiety was increased, the resistance to degradation also increased. The presence of an aromatic component in the hard block reduced the rate of hydrolysis but the degradation in mechanical properties was accelerated. Degradation studies on a series of polyesterurethanes having different compositions of hard and soft blocks have been performed utilizing an accelerated test method. Degradation was followed by titrimetry, mass loss, mechanical properties and infrared spectroscopy. As the number of methylene groups present within the polyester moiety was increased, the resistance to degradation also increased. The presence of an aromatic component in the hard block reduced the rate of hydrolysis but the degradation in mechanical properties was accelerated.