A novel cytocompatible graft copolymer of chitosan and L-lactic acid (CL) was prepared by grafting L-lactic acid onto the amino groups in chitosan without a catalyst. The structures of the CL graft copolymers were characterized by FTIR, C-13-NMR and X-ray measurements. Degree of substitution and side-chain length were evaluated from salicylaldehyde and elemental analysis. The tensile strength and water uptake of the CL copolymers films were investigated as a function of feed ratio of LA/CS. The influence of pH on the swelling behavior of the copolymer films was determined and interpreted. Fibroblast culture was performed to evaluate cell proliferation on the copolymers films. The results showed that the cell growth rate on the copolymers films is faster than chitosan obviously. (C) 2003 Elsevier Ltd. All rights reserved.