Although medical interest in individuals adopting the dress and life-style of the opposite sex goes back to antiquity, surgical intervention is a product of the last 50 years. In the last 15 years, evaluation procedures and surgical techniques have been worked out. Extended evaluation, with a one- to two-year trial period prior to formal consideration of surgery, is accepted practice at reputable centers. Cosmetically satisfactory, and often functional, genitalia can be constructed. Less clear-cut however, are the characteristics of the applicants for sex reassignment, the natural history of the compulsion toward surgery, and surgery's long-term effects. The characteristics of 50 applicants for sex reassignment, both operated and unoperated, are reported in terms of such indices as job, education, marital, and domiciliary stability. Outcome are reviewed. The results of long-term follow up data are discussed in terms of the adjustments of operated and unoperated patients.