Transsexualism has been understood as a disorder of the awareness of the own genderidentity. Transsexuals are rigidly convinced that they belong to the opposite sex, and they wish to acquire the external features of that sex. Most authors agree that transsexualism is a specific syndrome. Although several hypotheses from different fields of research exist, the origin of this sexual aberration is unknown. Because most transsexuals are not motivated for psychotherapy, and the outcome of this kind of treatment remains uncertain, surgical 'correction' of the sexual organs should be considered for a group of well selected transsexuals. A forty years old male transsexual underwent operative sextransformation. During a follow-up period of 2 1/2 years the results appeared to be satisfactory. There is an urgent need for closer cooperation amongst the different medical centers in the Netherlands, where sextransformation is performed.