Renal disease has been recognized as both a cause and a consequence of hypertension. Renal hypertension may be of vascular and nonvascular origin. Generally, the prevalence of hypertension increases with decreasing renal function, including more than 90% of patients with terminal renal failure. However, hypertension is more often found in glomerular than in interstitial disease. The pathomechanisms operative in renal hypertension are sodium retention with concomitant volume expansion, an increase in plasma renin activity or a combination of both factors. While mechanical intervention is usually tried in renovascular hypertension and in the rare cases with "urological" causes, no causal therapy is possible in most cases of renoparenchymal disease. However, as the normalization of blood pressure is the best proved way to stop or at least retard the progression of renoparenchymal disease, pharmacological intervention is mandatory even if the medication sometimes has side effects.