Trans-sexualism is a psychiatric disorder characterized by the conviction that one's gender identity does not conform to one's biological sex. The current Diagnostic and Statistical Manual of Mental Disorders gives 5 diagnostic criteria for trans-sexualism which most health care professionals accept. Although many trans-sexuals derive some gratification from assuming roles appropriate to their desired gender, a substantial number are convinced that only sexual transformation can bring meaningful relief of their feelings of despair. Approximately 2/3 of trans-sexuals who undergo sex reassignment procedures are improved at follow-up. A relatively advanced age and secondary trans-sexualism (transvestites and effeminate homosexuals) are risk factors for poor prognosis in those requesting sex reassignment. In recent decades the demand for sex reassignment has increased, as have the number and variety of psychological, hormonal and surgical treatments proposed. The operative procedures currently employed for sex reassignment give reasonably good esthetic and functional results, and in 1986 the Israel Ministry of Health permitted its government hospitals to perform them. A 23-year-old male trans-sexual is reported who underwent successful surgery for sex change and now, 1 year later, is satisfied with the result.