During the 20 minute LAD occlusion, 10 of 22 cats(45%) had no arrhythmias, and 12 cats(55%) had nonsustatined ventricular tachycardia. After release of occlusion, 5 of 22 cats(23%) had no arrthmias, and 17 cats(77%) developed sustained ventricular arrhythmias(ventricular tachycardia (n=5), ventricular fibrillation(n=12)). The 17 cats which had reperfusion arrhythmias were randomly divided and given normal saline(control(n=8)) or amiodarone(amiodarone group(n=9)). There was no difference on 2 groups. The reperfusion arrhythmias disappeared in 6 out of 9 cats(66.7%) vs none of 8 controls(P<0.01). We conclude that amiodarone seems to be the effective antiarrhythmic drug on reperfusion arrhythmias after release of LAD occlusion in anesthetized cats, and might be useful for the treatment of reperfusion arrhythmias in human.