Blend homogeneous films of chitosan and water-soluble methoxy poly(ethylene glycol)-b-poly(epsilon-caprolactone) (MPEG-b-PCL) diblock copolymer with different blend ratios were prepared by aqueous solution blending method. The water-soluble MPEG-b-PCL was synthesized using MPEG with molecular weight of 5000 g/mol and stannous octoate as the initiating system. The molecular weight of MPEG-b-PCL obtained from H-1-NMR was 5800 g/mol. FTIR spectra of the blend films showed that there were intermolecular bonds between chitosan MPEG-b-PCL. Thermal properties of the blend films strongly depended on the blend ratios. Scanning electron micrographs indicated that the blend films were homogeneous films. However, roughness of the blend films increased whereas transparency and moisture uptake decreased upon increasing the MPEG-b-PCL blend ratios. (c) 2008 Wiley Periodicals, Inc.