Last updated: 02/17/2009

An orchiectomy is done to treat cancer or, for other reasons, to lower the level of testosterone, the primary male sex hormone, in the body. Surgical removal of a testicle is the usual treatment if a tumor is found within the gland itself, but an orchiectomy may also be performed to treat prostate cancer or cancer of the male breast, as testosterone causes these cancers to grow and metastasize (spread to other parts of the body). An orchiectomy is sometimes done to prevent cancer when an undescended testicle is found in a patient who is beyond the age of puberty.

A bilateral orchiectomy is commonly performed as one stage in male-to-female (MTF) gender reassignment surgery. It is done both to lower the levels of male hormones in the patient's body and to prepare the genital area for later operations to construct a vagina and external female genitalia.

Some European countries and four states in the United States (California, Florida, Montana, and Texas) allow convicted sex offenders to request surgical castration to help control their sexual urges. This option is considered controversial in some parts of the legal system. A small number of men with very strong sex drives request an orchiectomy for religious reasons; it should be noted, however, that official Roman Catholic teaching is opposed to the performance of castration for spiritual purity.