Potassium disorders are common and may precipitate cardiac arrhythmias or cardiopulmonary arrest. They are an anticipated complication in patients with renal failure, but may also occur in patients with no previous history of renal disease. They have a broad clinical spectrum of presentation and this paper will highlight the life-threatening arrhythmias associated with both hyperkalaemia and hypokalaemia. Although the medical literature to date has provided a foundation for the therapeutic options available, this has not translated into consistent medical practice. Treatment algorithms have undoubtedly been useful in the management of other medical emergencies such as cardiac arrest and acute asthma. Hence, we have applied this strategy to the treatment of hyperkalaemia and hypokalaemia which may prove valuable in clinical practice.