Ligation of the left coronary artery in rats provides a relatively simple model for the assessment of antidysrhythmic compounds. This procedure results in severe arrhythmias in the initial postligation period (extrasystoles, bigeminae, tachycardia and fibrillation). Using this model we have compared the effectiveness of antiarrhythmic drugs which will be referred to class I, II and IV according to the VAUGHAN WILLIAM'S classification. All drugs have been shown to be antiarrhythmic against early occlusion arrhythmias. Especially the antiarrhythmics prevent the rhythm disturbances tachycardia and fibrillation. We conclude from the results that the coronary artery occlusion in rats is a valuable model to use in the screening of drugs for possible antidysrhythmic activity and with differing electrophysiological profiles.