Long-term habituation of male sexual arousal occurs when (a) short-term (intrasession) habituation occurs; (b) habituated arousal spontaneously recovers; (c) the magnitude of spontaneous remission decreases across habituation sessions; and (d) the number of trials to habituation decreases across sessions. Five undergraduate volunteers each had six sessions at one week intervals of 15 presentations of erotic audiotapes. For three weeks, the same audiotape was presented, and for each of the other three sessions a different audiotape was presented at every stimulus trial. As indicated by penile plethysmography and self-report, in the constant stimulus conditions the criteria for long-term habituation generally were met. By contrast, responses to variable stimuli remained consistently high. Theoretical and clinical implications of the habituation process are discussed.