The treatment of a specific situational phobia (of high level lavatory cisterns) is described. The method used was to utilize the autonomic excitation caused by vigorous muscular activity as an inhibitor of the situational anxiety. The patient was made to enter feared situations immediately after running close to the limit of toleration. The near lifelong phobia was removed in five short sessions with little psychiatric involvement. The method is attractive because of its basic simplicity, the rapidity of the response and the minimal demand on therapist time.