Mantled howler monkeys (Alouatta palliata) of both sexes and all age classes were observed rubbing urine on the soles of the feet and/or palms of the hands as well as the ventral surface of the tail and, occasionally, the throat. Instances of urine-rubbing were often associated with periods of troop movement or times of social stress. Intra-troop cohesion may be the primary function of such behavior. Other possible functions of urine-rubbing are discussed.