Hypoglycemia associated with renal failure is more common than generally thought. Its occurrence is often a marker of multisystem failure and has an ominous prognostic implication. Its pathogenesis is frequently complex and involves one or several mechanisms. In the evaluation of uremic hypoglycemia, the first step should be the exclusion of obvious causes such as insulin, oral hypoglycemic agent therapy, and the use of drugs known to cause hypoglycemia. Propranolol, salicylates, and disopyramide are among the most commonly implicated agents. Additional triggering events are alcohol consumption, sepsis, chronic malnutrition, acute caloric deprivation, concomitant liver disease, congestive heart failure, and an associated endocrine deficiency. When no obvious cause can be demonstrated, the hypoglycemia is referred to as spontaneous. Spontaneous uremic hypoglycemia has been attributed to deficiency of precursors of gluconeogenesis, that is, alanine, deficient gluconeogenesis, impaired glycogenolysis, diminished renal gluconeogenesis and impaired renal insulin degradation and clearance, poor nutrition, and, in a few cases, deficiency in an immediate counterregulatory hormone such as catecholamine and glucagon. However, the mechanism(s) seems to differ from one patient to the other. Dialysis also predisposes to hypoglycemia in uremia, possibly because of the chronic state of malnutrition. Postdialysis hypoglycemia is secondary to glucose-induced hyperinsulinemia, which is caused by the high glucose content in the dialysate. In uremic hypoglycemia, neuroglycopenic manifestations predominate because of frequent autonomic nervous system dysfunction and lack of catecholamine release in response to hypoglycemia. Its severity and duration are variable. Hypoglycemia should be suspected in any patient with renal failure who exhibits any change in mental or neurologic status. Detection of hypoglycemia should rely on frequent and careful glucose determinations in any patient with uremia.