Abstract: A silencing system for exhaust gases from internal combustion engines, comprising an intermediate silencing device for connection to the exhaust manifold of an internal combustion engine, and a final silencing device series connected to the intermediate silencing device, in which the final silencing device comprises, within an envelope, a number of spaced annular members, intersected by radial partition walls, forming series of chambers of different size, which occupy the peripheral portion of the envelope and open towards the axial portion of this latter, leaving this axial portion substantially free for passage of the flow of exhaust gases, and an idle fan is provided for acting onto the passage for the exhaust gases and onto a passage for additional air, which passages join downstream the fan into an exhaust nosepiece. Some annular members are made of a catalytically active material in order to exert a purifying action on the exhaust gases.