Conflicting reports regarding the influence of mental tasks on auditory fatigue have recently appeared in the literature. In the present study, 10 male subjects were exposed to a 4000-cps fatigue tone at 40 dB SL for 3 min under conditions of mental arithmetic and reverie. Temporary threshold shifts, as indicated by comparing pre- and post-fatigue thresholds, were consistently greater when subjects worked mental arithmetic during exposure to the fatigue tone than when they engaged in reverie.