Ambulatory blood pressure (BP) measurement has added a new dimension to the evaluation of abnormal BP in patients with various stages of renal disease. Although there is not complete consensus concerning the definition of normal values, a high prevalence of an abnormal circadian BP profile is noted in patients with essential hypertension with renal involvement (ie, microalbuminuria), in diabetic patients (particularly those with microalbuminuria or overt proteinuria), and in patients with primary chronic renal disease. Studies in diabetic patients point to an important role of both hypervolemia and disturbed autonomic innervation in the genesis of an abnormal circadian BP profile. In both patients with diabetic renal disease and patients with nondiabetic renal disease, retrospective studies suggest that an abnormal nocturnal decline in BP is associated with more rapid progression independent of 24-hour mean arterial pressure. The abnormal circadian BP profile persists in dialyzed patients, is ameliorated by long and frequent dialysis sessions, but is not completely normalized after successful renal transplantation.