This paper reports a safe, easy, effective, and one-step process to introduce a collagen layer onto a polyester-urethane surface for improving its biocompatibility and reducing acute inflammatory reaction. Collagen gel (COL) was spread onto the plasma-treated polyurethanes (PU) film to make PU-COL composite film by lyophilization. In this process, collagen on the interface was covalently immobilized to PU surface. Density of immobilized collagen molecules was examined to find the optimal experiment condition. The surface properties of the immobilized film were characterized by attenuated total reflection infrared spectrum and X-ray photoelectron spectroscopy to determine the efficiency of collagen immobilization. The results indicated that collagen chains had been grafted on PU surface because of plasma activation. To see if collagen modification can deduce acute inflammatory reaction and improve tissue guide regeneration, PU and PU-COL composite film were implanted subdermally in rats to analyze the effect of collagen immobilization. The reaction interface of PU-COL composite film and rat's tissue was observed by transmission electron microscope to analyze biocompatibility of PU-COL; unmodified PU film was used as control. The result showed that acute inflammatory reaction induced by PU-COL composite film had vanished gradually after 7 days and the material was embedded by tissue, almost forming a capsule. The capsule's wall thinned out gradually in the following days. Although the control group's inflammatory reaction did not vanish in I month and PU film embed in rat's tissue incompletely, PU implant migrated easily from the implant site. As a result, PU-COL composite film had most advantage in tissue guide regeneration and compatibility. (c) 2005 Wiley Periodicals, Inc.