Grafted-collagen films with poly(methyl methacrylate), poly(butyl methacrylate), and poly(styrene) were prepared by photoirradiation of the collagen films in the presence of respective monomers. Cell adhesion onto the films was investigated, and the amount of cells adhered onto every grafted films was almost the same as that onto the collagen film crosslinked with glutaraldehyde. Because the swollen grafted films are stronger than the collagen film, they are expected to be good biomedical materials.