We evaluated efficacy of sound as a deterrent for reducing deer (Odocoileus spp.)–vehicle collisions by observing behavioral responses of free-ranging white-tailed deer (O. virginianus) to pure-tone sounds within their documented range of hearing. Behavior of free-ranging deer within 10 m of roadways was not altered in response to a moving automobile fitted with a sound-producing device and speakers that produced 5 sound treatments documented to be within the hearing range of white-tailed deer. Many commercially available, vehicle-mounted auditory deterrents (i.e., deer whistles) are purported to emit continuous pure-tone sounds similar to those we tested. However, our data suggest that deer whistles are likely not effective in altering deer behavior in a manner that would prevent deer–vehicle collisions.