In general, severe hyperkalaemia produces classic electrocardiographic manifestations including tenting of T waves, widening of the QRS complex, loss of P waves, and eventually, sine waves and asystole. This report concerns a patient with chronic renal failure on maintenance haemodialysis who developed a severe hyperkalaemia associated with chest pain, manifested electrocardiographically by elevation of the S-T segment resembling acute myocardial infarction. After haemodialysis, serum potassium decreased and the electrocardiogram returned to normal. We review the literature and discuss the possible physiology of this electrocardiographic alteration.