Clinical investigations in the past few years have enhanced the understanding of the mechanisms of hyperkalemia in patients with ESRD. The results of these studies have led to modifications in the acute treatment and prevention of hyperkalemia in this patient population. They have confirmed the efficacy of intravenous insulin, while raising doubts about the utility of intravenous bicarbonate, for the acute treatment of hyperkalemia. Moreover, the beta-adrenergic agonist albuterol has been shown to be a useful adjunct to insulin for acutely lowering plasma potassium. Finally, there has been enhanced recognition of nondietary factors that can predispose to hyperkalemia in patients with ESRD, including prolonged fasting and the use of nonselective beta-adrenergic blockers. These new insights may improve the clinical management of hyperkalemia in patients with renal failure.