The technical possibility of surgical sex change has opened up a debate concerning the legitimacy and utility of carrying out such an intervention at the request of the transsexual. Diagnostic, psychological, medical and ethical arguments have been brought forth, both for and against. Nonetheless, anatomical transformation by surgical means has currently become a practice as the frequency of serious gender identity disorders is constantly progressing. After a brief introduction, the present paper will consider typological, aetiological and epidemiological aspects of transsexualism. Treatment of the sex change applicant is then defined and discussed in terms of psychological, psychiatric, endocrinological and surgical aspects. Finally, the question of post-operation follow-up will be examined.