We present a male patient who underwent a fluorescein sodium-guided brain tumor excision and experienced an anaphylactic reaction with severe hypotension and bradycardia. A 54-year-old, 70 kg man of American Society of Anesthesiologists status II was seen with a history of glioma. In the 80th minute of the operation, 20 mg/kg intravenous (i.v.) fluorescein sodium was injected after dural opening. A few minutes later, the anaphylactic reaction was diagnosed. Surgery was ended and the patient was delivered to the intensive care unit with intubation. Laboratory values were: immunoglobulin E, 332 U (upper limit 100 U); and elevated tryptase, 3.12 mg/dL. In view of the expanding use of fluorescein sodium in clinical procedures, physicians should be alerted to this rare but life-threatening adverse event. (C) 2010 Elsevier Ltd. All rights reserved.