Anesthesiologists are physicians who specialize in the prevention and treatment of pain. About five percent of all physicians are anesthesiologists. Unless you have had an operation, you may never have encountered an anesthesiologist. Anesthesiologists administer anesthetics before and during surgery and other medical procedures so the patient will feel no pain. Each year, more than 25 million surgical procedures are performed in the United States. These surgical procedures would not be possible without modern anesthesia techniques that block the pain of surgery.