1. This paper reports the attitude and behavioural changes and clinical outcome in 10 homosexuals treated with electrical aversion therapy. Two methods of aversion have been used, one in which electric shock was associated with erectile responses to deviant fantasies (used in all cases) and the other in which the shock has been associated with the deviant fantasy itself (used in 3 cases). Follow-up has ranged from three to one years. 2. Of the 10 patients, 7 showed significant changes in sexual attitudes following treatment, but in only three have these changes been sustained and in only one can the result be called completely successful. 3. The direct effects of treatment and the emotional reactions to it have been summarized. It is suggested that the changes produced cannot be adequately explained in S-R learning theory terms, and a more profitable approach is to consider the treatment as a method of changing attitudes comparable to methods investigated by social psychologists in a non-clinical setting. The stability of such attitude change will depend on its translation into behavioural change. From this view point, it becomes clear that aversion is one technique of attitude change amongst many, rather than a specific treatment for a particular condition. 4. The justification for using an inherently unpleasant method of modifying attitudes requires confirmation from controlled comparative therapeutic trials. Such a trial is now in progress.