A transmission belt is described which comprises a body made of a first elastomeric material, a plurality of teeth and a plurality of longitudinal cords buried in the body of the belt and a back. The belt has a working surface on said teeth and the working surface is at least partially covered by a covering made of a plastic and/or metal material. Defining the area comprised between the plane defined by the neutral axis of the cords, the working surface and the median transverse planes of two adjacent teeth as the unitary longitudinal section, the covering preferably occupies at least 25% of the unitary longitudinal section.