The number of patients developing end-stage renal disease (ESRD) as a consequence of hypertension is increasing and accounts for 25% of new cases of ESRD in the United States. However, the diagnosis of hypertensive ESRD is one of exclusion and no pathologic data corroborate this classification. Undoubtedly, these patients suffer from a variety of diseases, including accelerated hypertension and atherosclerotic disease of the large arteries. Also included are patients with an undiagnosed primary renal disease. The prevalence of these conditions in the hypertensive population is unknown. It is also proposed that mild to moderate hypertension can lead to ESRD. In support of this view, early investigators noted that nephrosclerosis was correlated with hypertension and/or left ventricular hypertrophy. More recently, in the Hypertension Detection and Follow-up Program, renal function was found to decline in some patients despite treatment. Data from the Baltimore Longitudinal Study of Aging indicate that the rate at which creatinine clearance declines with aging is correlated with blood pressure. A recent retrospective study reported that serum creatinine increased significantly in approximately 15% of treated hypertensive patients. However, in none of these studies was the presence of intrinsic renal disease definitively excluded. Furthermore, although an increase in serum creatinine or decline in clearance has been reported, progression to end-stage renal disease has not been documented. Therefore, additional studies are necessary to determine the frequency with which essential hypertension leads to end-stage renal disease.