Fungal damage of microfilm collections has been reported from many parts of the world, including the northeastern United States. Archival standards indicate that humidity and temperature control are primary factors in the prevention of fungal growth in microfilm storage facilities. Tests of fungal resistance of films treated with certain products, performed by an independent test laboratory using established industry standards, provide information as to their fungal resistance characteristics. A method of simple, inexpensive film protection, ethylene oxide dry cold sterilization, has been included in the test and has given promising indication of having merit. Vesicular film, diazo film, polyester and acetate bases and silver gelatin emulsion, Amprolene sterilized, have proven to be totally fungus resistant after one year in a super-saturated fungal growth environment.