Body temperatures exceeding 41.1 degrees C (106 degrees F) occur with relatively few conditions. In the unusual case reported here, the patient's temperature reached 42.3 degrees C (108.2 degrees F) during intravenous administration of bretylium for refractory ventricular fibrillation. The temperature started to drop as soon as the infusion was stopped and was close to normal within four hours. This appears to be the first report of extreme pyrexia resulting from use of this agent.