Cauterization (or cauterisation, or cautery) is a medical practice or technique of burning a part of a body to remove or close off a part of it. It destroys some tissue in an attempt to mitigate bleeding and damage, remove an undesired growth, or minimize other potential medical harm, such as infections when antibiotics are unavailable.

The practice was once widespread for treatment of wounds. Its utility before the advent of antibiotics was said to be effective at more than one level:

• To prevent exsanguination
• To close amputations

Cautery was historically believed to prevent infection, but current research shows that cautery actually increases the risk for infection by causing more tissue damage and providing a more hospitable environment for bacterial growth. Actual cautery refers to the metal device, generally heated to a dull red glow, that a physician applies to produce blisters, to stop bleeding of a blood vessel, and for other similar purposes.

The main forms of cauterization used today are electrocautery and chemical cautery—both are, for example, prevalent in cosmetic removal of warts and stopping nosebleeds. Cautery can also mean the branding of a human.