Halothane, a safely and easily administered anesthetic agent, is associated with liver damage only in the rare patient. Until a method is developed to predict which individuals will be affected adversely, the best protection we can provide for the patient is to monitor closely the postoperative period in every patient receiving halothane. If an untoward reaction referable to the liver is detected, the patient should not be exposed again to halothane. If there was no reaction, providing sufficient time had elapsed to allow the appearance of signs and symptoms of hepatic dysfunction, subsequent choices of anesthesia for this patient should be made by the anesthetist, based upon his experience and the requirements of the operation. Halothane may be the agent of choice in patients with chronic liver disease.