• 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 reviewed. The results of long-term follow-up are reported in terms of such indices as job, educational, marital, and domiciliary stability. Outcome data are discussed in terms of the adjustments of operated and unoperated patients.