A series of well-defined brush polymers, poly(oxy(11-(3-sulfonylpropyltrimethyl-glycinyl)undecylesterthiomethyl) ethylene-co-oxy(n-dodecylthio-methyl)ethylene)s (PECH-DMAPSm, where m is the mol% of the DMAPS [sulfobetaine] end group) were synthesized. The thermal properties and phase transitions of these polymers were investigated. The polymers were thermally stable up to 185 oC and were found to form favorably into multibilayer structures, always providing hydrophilic, zwitterionic sulfobetaine end groups at the film surface. Because of the presence of these sulfobetaine groups at the surface, the polymer films promoted HEp-2 cell adhesion and revealed biocompatibility in mice but significantly suppressed protein adsorption. These results collectively indicate that the sulfobetaine-containing brush polymers are suitable for use in biomedical applications, including medical devices and biosensors that require biocompatibility.