Abstract: Surfaces of articles made of polyethylene, polypropylene, crystalline dipolymers of ethylene with propylene, blends of two or more of the above, and blends of any of the above with elastomeric ethylene/propylene copolymers or with EPDM copolymers are prepared for painting by priming with a chlorinated polymeric material selected from a chlorinated polypropylene and chlorinated polypropylene containing carboxylic anhydride groups, and exposing to ultraviolet radiation. This treatment improves both dry and wet adhesion of paint to surfaces of articles made of single polyolefins as well as of their blends with elastomeric copolymers in which the latter constitute at most 50% of the total polymer.