A microscopic spot formation has been discovered in rolls of processed negative microfilm. It occurs most commonly as circular spots in the background and leader, but occasionally in the image lines, also. The silver is missing from the attacked area and has been redeposited in the surrounds, probably by an oxidation-reduction mechanism. Little damage to information recorded on the microfilm has occurred so far. However, the possibe occurrence of these spots has important implications in the archival storage of microfilm. Procedures for optimum storage and a gold protective processing treatment to prevent future damage are described. -- CCI