Graft polymerization of acrylic acid onto plasma-treated poly(ethylene terephthalate) (PET) films was used to prepare surfaces suitable for Collagen immobilization by dip-coating. Such surfaces could be used as matrices for smooth muscle cell cultures in tissue engineering. Contact angle measurements showed that plasma-treated and grafted PET films undergo considerable surface reorganization during storage under ambient conditions. However, after Collagen immobilization the contact angle remained relatively stable. The amount of Collagen initially attached to the film surface increased with increasing poly(acrylic acid) graft density, but subsequent washing in water led to significant Collagen loss. This loss could nevertheless be substantially reduced by thermal crosslinking of the Collagen in the range 110-130 degreesC. Atomic force microscopy (AFM) observations suggested that the washed crosslinked Collagen has a very similar structure to that of the un-crosslinked Collagen.