A process for coating metals, selected from aluminum and its alloys, zinc and its alloys, and galvanized or alloy-galvanized steel, in which the metal is given a weather-resistant protective coating, wherein the metal is cleaned if necessary, and thereafter subjected to a conversion treatment; optionally flushed with water and/or dried; brought into contact with a coating agent which comprises aliphatic cross-linking urethane resins, cross-linking agents, anti-corrosion pigments, one or more organic solvents and/or water and, if desired, other active or auxiliary substances; and then cured.