Three instances of rheumatic nephrosclerosis are described in patients with chronic rheumatic valvular heart disease. The underlying mechanism of this renal lesion consists of an obliterating rheumatic endarteritis, involving mainly medium-sized and small arteries of the renal cortex. The arterioles take relatively little part in these changes. The widespread occlusive vascular disease gives rise to innumerable microscopic infarctions, resulting in a coarsely granular external surface of the kidneys.A similar granular appearance of cerebral convolutions may or may not occur in these cases, depending on whether the small meningeal and cortical vessels of the brain are extensively involved.