Forty-eight male patients with long-standing histories of deviant sexual behavior received medroxyprogesterone acetate and milieu therapy for up to 12 months. Forty subjects responded positively, all within 3 weeks, with diminished frequency of sexual fantasies and arousal, decreased desire for deviant sexual behavior, increased control over sexual urges, and improvement in psychosocial functioning. Improvement in deviant sexual behavior and psychosocial functioning was maintained after treatment ended, and there was no evidence of permanent physiological changes. The author suggests that medroxyprogesterone acetate associated with counseling may be the treatment of choice for patients with long-term deviant sexual behavior. He discusses the ethical issues involved.