THE place of nephrectomy in the treatment of hypertension forms a small but important aspect of the main subject of " Hypertension in Urology " ; small because among the large numbers of individuals who suffer from hypertension only a very few will benefit from nephrectomy, but important since to these few this benefit will be lasting. On account of limitation of space it is not possible to give a comprehensive review of this subject but only to pick out the salient features which are especially important in making a correct choice of the patients who will benefit from the loss of a kidney.Incidence.-The hypertensive patient who is suitable for nephrectomy is found in all decades of both sexes, and if the choice of case is made carefully the elderly patient may do well, but a higher proportion of good results will occur in the younger age groups and in females.The low incidence among cases of hypertension of those who will benefit from nephrectomy is clearly demonstrated in the papers of Braasch (1942Braasch ( , 1952 and Ratliff et aE. (1947). Unilateral renal lesions were demonstrated by the former in 4 per cent. and by the latter in 5.5 per cent. of the total number reviewed, but only a fraction of these small numbers were regarded as suitable for operation.Clinical Features.-Suitable cases fall into two clinical groups: one in which a routine investigation for hypertension reveals a possible renal cause which has previously been unsuspected and symptomless ; the other in which there are definite symptoms referable to the renal tract, usually associated with some florid pathological lesion. This group contains the conditions which by themselves justify nephrectomy. It does not provide such a high proportion of good results.In the first group unilateral pyelonephritis is frequently found, and when it is symptomless the prognosis is better. This lesion is the " Goldblatt " kidney of human pathology and offers a fascinating problem. The histological features illustrated in Figs. I , 2, and 3 may be clinically quite silent and can be found in kidneys removed at all ages. The symptomless quality of this lesion and the wide range of ages in which it is found suggest that it may be progressive, ending as the small atrophic kidney which is frequently found in cases of nephrogenic hypertension. It is unfortunately often bilateral.Investigation.-It is not necessary to proceed to specialised investigation of divided renal function in every case of hypertension. This should be done if the patient is under 45 years or the clinical examination of the urine and general tests of renal function suggest that renal abnormality is present. The primary investigation of divided renal function is intravenous pyelography ; with this is associated divided renal function studies with analysis of the renal urines, particular attention being paid to the pH and urea concentration. Chromocystoscopy should also be done.In this particular form of renal investigation it is probable that aortography as described and practised by Griffiths (1950...