Background : Epinephrine used in surgery to provide hemostasis may elicit ventricular arrhythmias. A desirable anesthetic would not sensitize the myocardium to exogenously administered epinephrine. So the effect of sevoflurane, which was introduced to clinical anesthesia recently, on cardiac arrhythmias induced by the infusion of epinephrine was compared with those of halothane which was already known to epinephrine-induced arrhythmia in the 14 mongrel dogs. Methods : The authors compared the arrhythmogenicity(three or more premature ventricular contractions, PVCs)of intravenously administered epinephrine in 14 mongrel dogs who were randomly assigned to receive sevoflurane(1.7 vol%) or halothane(0.75 vol%) anesthesia equipotently. The arrhythmogenic doses of epinephrine determined in this comparative study were expressed by both infusion rates of epinephrine during sevoflurane and halothane anesthesia. Results : The mean values of the arrythmogenic infusion rates of epinephrine were 27.1 7.6 g/kg for sevoflurane and 2.7 0.8 g/kg for halothane. Conclusions : We concluded that the arrythmogenic doses of epinephrine during sevoflurane were significantly higher than those during halothane anesthesia. (Korean J Anesthesiol 1997; 33: 1∼5)