Abstract: A method and apparatus for producing splined driving belts from a flexible annular element of vulcanized rubber, having a flattened rectangular section and mounted around two support rollers operated in rotation so as to move the annular element according to the direction of its longitudinal extension. A first set of knives transversely penetrates into the annular element for producing one series of longitudinal cuts parallel to the annular element according to a predetermined depth and in an inclined direction relative to the perpendicular line of an operating surface of the annular element itself and a second set of knives produces a second series of longitudinal mutually-parallel cuts inclined with respect to the cuts of the first series so as to form a series of longitudinal grooves in the annular element.