The electrocardiographic manifestations of hyperkalemia have been well described. We report the case of a patient with permanent atrial fibrillation for 13 months, who converted to normal sinus rhythm after treatment for hyperkalemia. This is the first case of hyperkalemia-induced conversion of permanent atrial fibrillation to sinus rhythm with a well-documented transitional tracing of atrial arrest. J Cardiovasc Med 11:000–000 Q 2010 Italian Federation of Cardiology.