Many years ago Thai society considered transsexualism (Gender identity disorder or Gender dysphoria) which is commonly known as Kathoey (a word originally used to denote hermaphrodites), Sao Prapet Song or Tut (as in ‘Tootsie’) were low class citizens, dirty dressing and had to hide in a dark corner selling their services as prostitutes. This made us unwilling to do sex reassignment surgery for this group of people because the idea of eradicating normal sexual organs for the purpose that was not accepted by the society. Consequently the authors have experience in cases where these people wandered seeking doctors who had no competency nor enough experience to do the surgery. The authors could not inhibit the desire of these people who usually suffer from gender identity disorder from strongly wishing to change their genital sex to the sex they want. The outcome of the surgery was not satisfactory for the patients. There were complications and sequelae which caused the authors to correct them later which might be more difficult than doing the original surgery. In addition there were more studies about the etiology and affect of the disorder on these people that changed the social point of view. The women who wanted to be a him and men who would like to
be a her should be considered as patients who need to be cured to set the harmony about their genetic sex and
the desire to be the opposite sex and also to be regarded by others as a member of that other sex. The treatments of transsexualism usually begin with conventional psychiatric and endocrinological treatment to adjust the mind to the body. For those who failed conservative treatment in adjusting the mind to the body then sex reassignment surgery will be the only way to transform their body to their mind and give the best result in properly selected patients.
Preecha Tiewtranon, the pioneer in sex reassignment surgery in Thailand, did his transsexualism case in 1975 together with Dr.Prakob Thongpeaw. Sex reassignment surgery has been taught in Chulalongkorn University Hospital since 1983. (At present, it is the only medical school in Thailand that has sex reassignment surgery systematically taught and with good results). There have been many versions of development of the surgical techniques to gain better and better results.

Keywords: Sex reassignment surgery, Kathoey, Tut, Sao Prapet Song