Polystyrene dishes whose surface was modified with a 2-chloroacetamidomethyl group were prepared by treatment of commercial dishes with an amidomethylating solution containing N-methylol-2-chloroacetamide. XPS analysis showed that most of the benzene rings in the polystyrene were substituted with the 2-chloroacetamidomethyl group. The 2-chloroacetamidomethyl group was converted to a aminomethyl, a 2-hydroxy-actamidomethyl, or a 2-alkyloxy-acetamidomethyl group. These reactions were carried out without deformation and loss of transparency of the dishes.