Chinese Hamster Ovary( CHO) cells were cultured on the surface-modified polymers described in the previous study( "Polymer Surfaces for Cell Adhesion. 1. Surface Modification of Polymers and ESCA Analysis, " J. of KOSOMBE, Vol. 10, No. 1, 43-51, 1989). Among the physicochemical treatment methods. the chloric acid treatment was found to be the best method of rendering the polymer surfaces adhesive for CHO cells probably due to the high density of hydroxyl groups on the surface. Among the biological methods, the fibronectin treatment was best for CHO cell-compatibility probably due to specific active sites existed on the tell-binding domains of the fibronectin structure. When we compare the cell-compatibility of the chloric acid - and the fibronectin -treated PET surfaces, the number of cells attached on the surfaces were increased by 460.5 % and 559.0 % and, respectively, after 32 hr CHO cell culture, compared to that of untreated PET.eated PET.