n. hardening of the arteries and arterioles of the kidneys. Benign nephrosclerosis is associated with essential hypertension. There is preferential involvement of the preglomerular arterial vessels, primarily the afferent arteriole and the interlobular artery. The classic arterial lesion, which is termed arteriolosclerosis, involves replacement of smooth muscle cells in the media of the vessel by connective tissue. There is often evidence of ischaemia in the glomerulus and *tubulointerstitium. Functionally there may be some degree of renal impairment. End-stage renal failure is uncommon, but more likely to occur in Afro-Caribbeans. Malignant nephrosclerosis is the hallmark of *malignant hypertension, with arterioles showing mucoid change, endothelial cell swelling, and fibrinoid necrosis. The lumen of the vessel is reduced and red cells fragmented in their passage through the narrowing. The kidney shows petechial haemorrhage on the subcapsular surface, with mottling and areas of infarction. Malignant nephrosclerosis can lead to a very rapid destruction of renal function and is recognized as a potential cause of acute renal failure.... nephrosclerosis