The renal function was observed by the method of renal clearance and thegeneral tests of urine on the 99 cases of the old ages over 60 years old, at an almshouse. in health and hypertension. And the ressults were as follows. 1. In the cases with normal blood pressure, both the glomerular filtration rate and the renal blood flow ran parallel to age and decreased in comparative speed after 60 years old, and the filtration fraction showed no difference with that of youth and the reabsorption rate of the renal capillaries declined in some degree. 2. In the old age, with hypertension, the glomerular filtration rate showed a insignificant decline in comparison with that of the cases with normal blood pressure, and it declined with age. And the renal blood flow showed a significant decline and it was not parallel to age, but it seemed to have a relation with the ascending of arterial blood perssure in some degree. 3. Since the above results, it was thought htat the hypertension of old age was similar to the essential hypertension of youth and there was a stationary nature of the pathogeny.