An ion implantation process for plastics is disclosed which materially enhances their surface hardness and their resistance to chemical attack. The plastics include the polycarbonates, the acrylics and their combinations, and ultra high molecular weight polyethylenes. The plastics are ion implanted by energetic ions such as aluminum, magnesium, silicon, titanium, yttrium, fluorine and chlorine ions. Such ion implanted plastics, in their transparent form, find uses such as aircraft, spacecraft, auto transparencies, lenses for safety and eyeglasses and contact lenses, face and gas masks and the like. In their non-transparent form, the ion implanted plastics are useful as ball bearings, safety helmets, floor coverings, appliance and auto moldings and the like.