A copolyester blend resistant to ultraviolet radiation includes a polyethylene terephthalate based copolyester having 1,4-cyclohexanedimethanol; an effective amount of an ultraviolet radiation absorber selected from the group consisting of benzoxazinones, dimeric benzotriazoles, triazines and mixtures thereof; and from 5 mol % to about 40 mol % isophthalic acid residues present in the copolyester wherein the mole percent is based on 100 mole percent of dicarboxylic acid or equivalents. The copolyester blend is useful in making UV radiation resistant thermoformed articles.