Abstract: A noise-suppressed timing belt pulley and a method of making the same is disclosed. The pulley has a toothed face for engaging a toothed timing belt and a pair of flanges for guiding the belt. Air holes are formed in the flanges in positions aligned with the spaces between the teeth of the pulley. Air passages are formed in the rim of the pulley. A channel is formed in the valleys between adjacent teeth between and connecting the air passages. The combination of air holes in the flanges, air passages formed in the rim and the channels formed in the tooth valleys greatly reduces the noise generated by an operating timing belt transmission.