Biodegradable aliphatic polyetheresteramides copolymers (PEEAs) were synthesized from epsilon-caprolactone, 6-aminocaproic acid, and poly(ethylene glycol) (PEG) by melt-polycondensation method. FTIR, H-1 NMR, differential scanning calorimeter, wide-angle X-ray diffraction, and thermogravimetric analysis/differential thermogravimetry were used to characterize the PEEAs. The tensile testing, water absorption and hydrolytic degradation behavior were also studied. With the increase in PEG content, the water absorption increased. The rate of hydrolytic degradation depended on the copolymers' hydrophilicity and crystallinity. PEEAs with a relatively low content of PEG still retain good tensile properties. (c) 2008 Wiley Periodicals, Inc.