We report the case of a 78-year-old woman, with previous narrow QRS atrial fibrillation, who in the presence of mild digoxin intoxication and severe hyperkalaemia, caused by chronic renal failure and usage of potassium sparing drugs, presented on her ECG two distinct wide QRS tachycardias. Initial treatment with low doses of procainamide resulted in severe bradycardia. Her original rhythm was restored after partial correction of hyperkalaemia with haemodialysis under continuous infusion of lidocaine. The electrocardiographic manifestations of hyperkalaemia and digoxin intoxication as well as the effect of lidocaine and procainamide on hyperkalaemia-induced wide QRS tachycardias are discussed.