The western grey kangaroo, Macropus fuliginosus, is a large-bodied kangaroo that engages in pentapedal locomotion at low speeds and bipedal hopping at high speeds. The tail is thought to have functional roles in both of these modes of locomotion. In pentapedal locomotion the tail acts as a ‘fifth limb’ to support the body weight together with the forelimbs while the hind limbs are drawn forward. The tail has also been suggested to have a role as a counterbalance during bipedal hopping. On the basis of these functional roles for the tail in locomotion, the caudal musculature of the western grey kangaroo was dissected and described in this study. The arrangement of the caudal musculature showed particular adaptations for the role of the tail in both pentapedal locomotion and bipedal hopping.