The electrical resistances of thin films of 24 metals, deposited on glass substrates (near room temperature) by evaporation, sputtering, or electroplating, have been measured before and after artificial aging by heatingin vacua. Reductions in resistance of 25 to 50% as a result of aging were commonly noted. Evaporated films were reduced from approximately 2&rgr;bto 1.3&rgr;b(resistivity of the bulk metal) and sputtered films from 4–10&rgr;bto 1.5–1.8&rgr;b. A preferred aging temperature, specific to each metal but influenced somewhat by film thickness, was noted. This temperature agreed closely with the temperature of recrystallization of the metal. Thin metal films, as usually deposited, appear to be in a state of strain not associated with the bulk metal as it crystallizes from the melt. The application of heat energy to the film promotes the removal of strains, occluded and adsorbed gas, and the growth of the crystallites of the film. These concurrent actions reduce the electrical resistance of films of 1000 A thickness to a value usually in the range 25–75% above that of the bulk metal.