Selenium (Se) is a trace element that participates as a cofactor in several enzymes (selenoproteins) which act in the regulation of thyroid hormone metabolism, enzymatic antioxidant defenses and the immune system. Se deficiency has been linked to atherosclerosis-related cardiovascular disease, increased risk of viral infections and even with an increased risk of mortality. Low serum Se levels are a frequent finding in patients with acute kidney injury or chronic kidney disease. The relationship between hyposelenemia and the comorbidities associated with renal disease has not been extensively evaluated. It has been reported that both low serum Se levels and renal insufficiency are associated with an increased risk of coronary heart disease mortality and an increased risk for all-cause mortality in adults older than 35 years. A recent report has suggested that hyposelenemia may contribute to immune dysfunction, increasing the risk of death from infectious disease in hemodialysis patients. Some studies have reported that Se status and immune function improve after oral and intravenous Se supplementation in renal patients, reducing the products of oxidative stress. In summary, although there are intriguing relationships between Se physiology and several derangements and comorbidities associated with acute and chronic kidney disease, only a few studies have analyzed the clinical consequences of hyposelenemia in these patients to date. Available data are encouraging and stimulate interest in further studies to clarify the real extent of Se deficiency and the need for Se supplementation in patients with kidney disease.