There is a difference between corrective surgery for the sex organs and sex change. Corrective surgery fixes deformity affecting the sex organs to achieve agreement between a person’s exterior and chromosomal make-up and his or her sex organs. This kind of surgery is permissible because what it achieves is treatment and not the altering of Allah’s creation or imitation of the opposite sex.
A sex change operation, however, means that healthy males or females suffering from no deformity, who are able to marry and reproduce, choose to undergo elective surgery to transform themselves into the appearance of the opposite sex.
This kind of surgery is prohibited by Islamic Law because it is altering Allah’s creation needlessly and in vanity. Allah relates to us that Satan says: “And I shall order them and they will alter Allah’s creation.” [Sûrah al-Nisâ’:119].
It is also the most extreme form of imitating the opposite sex. The Prophet (peace be upon him) said: “Allah curses men who imitate women and women who imitate men.”