In 27 patients with acute myocardial infarction (MI) and their infarct-related coronary artery being completely occluded who received thrombolytic therapy or percutaneous transluminal coronary angioplasty, reperfusion was confirmed by immediate coronary angiography in 24. Reperfusion arrhythmias (RA) occurred in 19 (79.2%) of the patients, including ventricular arrhythmias in 13 (54.2%). Ventricular fibrillation and sustained ventricular tachycardia developed in 2 (8.4%) and accelerated idioventricular rhythm in 5 (20.8%), the latter was a reliable indicator of coronary recanalization. Transient sinus bradycardia or AV block occurred in 10 (66.7%) of the 15 patients with inferoposterior MI. The occurrence of RA was not related to the duration of ischemia; ventricular RA was also not related to the location of MI and the occurrence and severity of ischemic arrhythmias before reperfusion.