Summary:Three patients who developed advanced or complete atrioventricular (AV) block as a complication of acute inferior myocardial infarction are presented. Block occurred when the sinus rate exceeded 110 to 130 per minute and 1:1 AV conduction was established below this rate. There was no associated ventricular bradycardia and thus no indication for temporary transvenous pacing. Complicating ventricular arrhythmias occurred and their management in the presence of impaired AV conduction is discussed; one such arrhythmia developed late in in the patient's hospital course, after he had left the coronary care unit. Late arrhythmias now, account for approximately one third of the deaths from acute myocardial infarction in this hospital and the provision of a subacute monitoring area following intensive coronary care is discussed.