Transsexualism is much more common than people think. Male to female transsexuals (MTF) outnumber female to males (FTM) by about three to one, but the statistics vary. Current estimates are approximately 1 in 10,000 for biological males and 1 in 25,000 for biological females.

There have been lots of studies to look at the prevalence of transsexualism. DSM-IV (1994) quote that 1 in 30,000 biological males and 1 in 100,000 biological females seek gender reassignment surgery in the USA. A European, population-based study in Amsterdam, which was carried out over a period of over four decades treating over 95% Dutch transsexuals, found figures of 1 in 10,000 assigned males and 1 in 30,000 assigned females as suffering from gender dysphoria. When you include the wider world, prevalence rates can be as high as 1 in 4,500 for assigned males and 1 in 8,000 for assigned females. In certain countries, particularly Brazil and Thailand, there is even evidence suggesting the actual rates might be as high as 1 in 500 births overall.

It is important to understand the difference between transgender and transsexual individuals when trying to understand how common it is. Transgender is an umbrella term used to describe the diverse group of people whose gender identity (whether on the inside or the outside) differs from that usually associated with their birth sex. Transgender individuals therefore include a wider range of people, including cross-dressers or transvestites which comprise of a much larger number of individuals than transsexuals. Estimating the number of transgendered people is obviously very diffcult, largely because it is often under-reported or conducted in private. Researchers estimate that the percentage of men who have cross-dressed is quite high, perhaps as much as 50%, with about 5-10% doing this on a regular basis.

Fortunately, now that transsexualism is becoming increasingly understood and that specialist services are evolving, it is becoming much easier to measure. Previous studies have been limited by the fact that it has been impossible to measure those individuals who are untreated or hidden from professionals who can help them. More recent studies suggest that worldwide it may be as common as 1 in 5000 people. In a city of 100,000 inhabitants, there could be as many as 20 transsexuals, if not more!