Hypertension is a common finding in chronic hemodialysis (HD) patients. Cardiovascular (CV) disease is the leading cause of death in this population, and hypertension is a significant risk factor for CV events. Understanding the etiology of hypertension in chronic HD patients is critical in order to optimize treatment and reduce the morbidity and mortality associated with hypertension. Although the pathogenesis of hypertension in HD patients is multifactorial, two of the major risk factors are increased extracellular volume and sodium intake. Control of extracellular volume has been shown to normalize blood pressure (BP), but this normalization lags behind the extracellular volume contraction ("lag phenomenon"). A sodium load leads to an increase in BP by causing an increase in extracellular volume, resulting in a transient increase in cardiac output and an increase in total peripheral resistance. Sodium may be implicated in the hypertension of end-stage renal disease (ESRD) patients through hypervolemia-independent mechanisms. Aggressive control of extracellular volume and dietary sodium intake can normalize BP in chronic HD patients and reduce the morbidity associated with hypertension-related CV disease.