Cryosurgery (cryotherapy) is the application of extreme cold to destroy abnormal or diseased tissue.

Cryosurgery comes from the Greek cryo (κρύο) meaning icy cold and the word surgery (cheirourgiki - χειρουργική) meaning literally hand work or Handiwork

Cryosurgery is used to treat a number of diseases and disorders, especially skin conditions.

Warts, moles, skin tags, solar keratoses, and small skin cancers are candidates for cryosurgical treatment. Some internal disorders are also treated with cryosurgery, including liver cancer, prostate cancer, cervical disorders and, more commonly in the past, hemorrhoids. Although found to be effective, this method of treatment is only appropriate for use against localized diseases with no metastasis.

Cryosurgery works by taking advantage of the destructive force of freezing temperatures on cells. At low temperatures, ice crystals form inside the cells, which can tear them apart. More damage occurs when blood vessels supplying the diseased tissue freeze.

In the past, the most common method to freeze was using liquid nitrogen as the cooling solution. The super-cooled liquid may be sprayed on the diseased tissue, circulated through a tube called a cryoprobe, or simply dabbed on with a cotton or foam swab. Less frequently, doctors use carbon dioxide "snow" formed into a cylinder or mixed with acetone to form a slush that is applied directly to the treated tissue. Recent advances in technology have allowed for the use of Argon gas to drive ice formation using a principle known as the Joule-Thomson effect. This gives physicians excellent control of the ice, and minimizing complications using ultra-thin 17 gauge cryoneedles.

Cryosurgery is a minimally invasive procedure, and is often preferred to more traditional kinds of surgery because of its minimal pain, scarring, and cost; however, as with any medical treatment, there are risks involved, primarily that of damage to nearby healthy tissue. Damage to nerve tissue is of particular concern.

Patients undergoing cryosurgery usually experience minor-to-moderate localized pain and redness, which can be alleviated by oral administration of an analgesic (such as acetylsalicylic acid (aspirin) or ibuprofen) and application of topical steroid cream. Blisters may form, but these usually scab over and peel away.