Life threatening hyperkalaemia (> 7.0 mmol/l) is commonly associated with acute renal failure. Moderate hyperkalaemia (6.1-6.9 mmol/l) is also common and well tolerated in patients with chronic renal failure. Renal failure is the most common cause of hyperkalaemia although other causes to consider include drugs (potassium sparing diuretics, angiotensin converting enzyme inhibitors), hyperglycaemia, rhabdomyolysis and adrenal insufficiency. Hyperkalaemia affects the cardiac conducting tissue and can cause serious arrhythmias including ventricular fibrillation and asystolic arrest. Therefore it is important to treat hyperkalaemia promptly in the emergency department. This paper evaluates the therapeutic options available for treatment of hyperkalaemia.