There is described a toothed belt comprising an elastomeric material body, in which a plurality of longitudinal filiform resistant inserts is embedded, and a toothing coated by a coating fabric. A resistant layer that increases the resistance to abrasion and thus the resistance to wear of the toothed belt is adhered over the coating fabric. The resistant layer comprises a vulcanisation agent and more than 75% of an elastomer formed by at least one copolymer modified with an unsaturated carboxylic acid salt and obtained from a dien monomer and a nitrile group-containing monomer. The resistant layer is advantageously separated from the fabric and is calendered on the fabric itself.