Toothed belt for use in contact with oil and comprising a body and a number of teeth extending from at least one surface of the body; the teeth are coated by a fabric; a resistant layer comprising a plastomer based on fluorine with the addition of elastomeric material, in which the plastomer is present in a larger quantity than the elastomeric material, is applied by adhesion onto the coating fabric. The elastomeric material forming the body of the belt is a copolymer obtained from a dienic monomer and a monomer containing nitrile groups, in which the nitrile groups are between 33% and 49%, preferably 39%, in weight with respect to the copolymer.