[Transsexualism].

According to the literature, the transsexual phenomenon can be assessed as a distinct psychiatric illness. Transsexualism, a rare but spectacular disorder, realizes a gender identity reversal raising questions regarding systems of psychiatric diagnosis, nosology and treatment. A better clinical knowledge of this "experiment" and its follow-up allow studying processes contributory to marked deviation of gender identity and furthering concepts of development of masculinity and feminity. Current research deals with hypotheses that can be stated as testable propositions about underlying dynamics in various fields: learning factors, psychoanalytic components and psycho-biological data. Focusing on the early infantile development and the environmental influences reflects a variety of non specific psychogenetic precursors. The treatment of "gender dysphoria syndrom", i.e. hormonal treatment, sex-reassignment surgery and psychotherapic processes, aims towards réduction of psychic pain and social adjustment in the cross-gender role. Transsexual phenomenon largely overlaps the psychopathological area; beyond surgical and medical aspects, social implications and legal positions refer to an ethical problem.