Numerous reports have documented cardiac arrhythmias in animals and man during halothane anesthesia, Cardiac arrhythmia may occur regularly with halothane anesthesia, being related to several factors; fright, overdoasge of atropine, surgical stimvlation in light anesthesia, hypercapnia and intravenous injection of epinephrine. The authors experienced a case of severe cardiac arrhythmia induced by fialothane anesthesia and treated by change of anesthetic agent to ether.