The effect of sevoflurane on cardiac arrhythmias induced by the infusion of epinephrine into dogs was compared with those of isoflurane and halothane. The arrhythmogenic doses of epinephrine determined in this comparative study were expressed by both infusion rates of epinephrine and the corresponding plasma levels obtained by a series of three-minute epinephrine infusions during sevolurane, isoflurane, and halothane anesthesia at 1.25 MAC. The mean values of the arrythmogenic infusion rates of epinephrine and the corresponding plasma levels were 17.3 microg/kg/min and 275.7 ng/ml for sevoflurane, 6.7 microg/kg/min and 149.2 ng/ml for isoflurane and 1.9 microg/kg/min and 39.1 ng/ml for halothane, respectively. These results indicate that the arrythmogenic doses of epinephrine during sevoflurane and isoflurane anesthesia were significantly higher than those during halothane anesthesia.