The potential danger of anesthetizing a patient on beta-adrenergic blockade therapy has long been recognized. The cases of 73 patients taking propranolol and anesthetized for non-cardiac operations were reviewed with regard to preoperative administration of propranolol and intraoperative and postoperative complications. Of these patients, 72 percent took propranolol to within 24 hours of operation and 85 percent took it to within 48 hours. The mean dose of propranolol was 77 mg/day (range, 10 to 320 mg/day). Anesthetic technics and agents included enflurane, halothane, N2O-narcotic-relaxant, and spinal anesthesia. There were only three episodes of hypotension, all of which responded to a decreased depth of general anesthesia, IV fluid administration, and, in one patient, a small dose of a vasopressor. There were no intraoperative or postoperative deaths. It is concluded that if propranolol is indicated for medical control of the patient's symptoms, it need not be discontinued before surgical anesthesia.