During the past 3 years, 3 patients undergoing intermittent hemodialysis (or about to do so) in our hospital developed a third-degree atrioventricular block while being treated with verapamil for blood pressure or supraventricular arrhythmia. In the 3 cases, mild hyperkalemia was concomitant. The medical history of these patients revealed no intrinsic cause of atrioventricular conduction disturbance. We report herein the 3 cases and draw attention to the risks of atrioventricular block in this particular context.