27 patients with hypertension and persistent proteinuria were investigated by renal biopsy. The 13 patients without structural glomerular abnormalities were younger and had less proteinuria than the other 14, but otherwise the two groups had similar clinical features. 6 of the 14 had diffuse glomerular abnormalities; the other 8 had segmental sclerosing lesions, which were mainly in the hilum of the glomeruli, as seen in states of glomerular overload. Glomeruli in all groups were larger than those in normotensive people. It is possible that hypertension causes glomerular enlargement, proteinuria, and segmental glomerular lesions because of loss of functioning glomeruli due to ischaemia.