It is currently unclear whether the auditory system contains mechanisms dedicated to processing motion information, analogous to those known to exist in the visual system. If so, the auditory system should demonstrate selectivity to velocity, and its scalar components (direction and speed). In the visual domain, motion adaptation results in direction-specific changes in perceived speed. Here we investigated whether similar effects can be elicited using moving auditory stimuli. Auditory motion in the horizontal plane was simulated using individually measured head-related-transfer functions. Subjects adapted to unidirectional auditory motion (60s initially, 10s top-up between trials), after which they judged the relative speed of sequentially presented reference and test stimuli moving in opposite directions. Three interleaved reference speeds (8, 16 and 24 deg/s) were used for each adaptor speed (8, 16 and 24 deg/s). To obviate the use of spatial or temporal cues in isolation, the duration of each test stimulus was randomly jittered. Results revealed a systematic reduction in the perceived speed of stimuli moving in the adapted direction, the magnitude of which increased with adaptor speed. These results are compatible with the hypothesis that both the auditory and visual systems directly encode motion information.