Sound spectrographic analysis of recordings of vocalizations of red colobus, Colobus badius, made on two brief visits to the Kibale Forest, Uganda, reveals a graded sound system as described by Hill and Booth [1957], Within 300 calls analyzed, three categories of sounds were discerned (fig. 1-3), all connected by intermediate forms (fig. 4 and 5). The extensive grading of the sounds contrasts with vocalizations of Colobus guereza and C. polykomos most of which are discrete rather than graded. This difference may be attributable to emphasis on vocal communication between troops in the black and white colobus and emphasis on intra-troop communication in the larger groups of the red colobus.