Surface functionalization of biodegradable poly-l-lactic acid(PLLA) was achievedby plasma coupling reaction of chitosan. The structure of modified PLLA surfaces was characterized by contact angle measurements and X-ray photoelectron spectroscopy. Two cell lines, L929 (mouse fibroblasts) andL02 (human hepatocytes), were cultured on the modified PLLA surface. It was found that cells cultured on this film could hardly spread and tend to become round, and the film was demonstrated to be a poorly adhering substrate. However, cells grown on this substrate can proliferate at almost the same speed as cultured on a glass surface. These results suggest that the new substrate can be used to control the morphology of cells, and has potential applications in tissue engineering. It may be helpful in understanding the mechanism of the switch between cell phases of growth and differentiation, which is necessary for the design of tissue regeneration biomaterials.