The surface photooxidation of Styrene/2-(2-Hydroxy-3-Vinyl-5-Methylphenyl)-Benzotriazole copolymers ( lambda greater than 300 nm) has been monitored by ESCA. The rate of oxygen uptake is shown to be dependent on the concentration of HVB in the surface. At concentrations less than 1% the rate appears to be very similar to that of unstabilized polystyrene and polystyrene stabilized with hydroxy-methylphenyl-benzotriazole as a 0. 5% additive. The data indicate that HVB is not capable of photostabilizing the surface. Transmission ir data suggest that the bulk material is photostabilized.