In 1913 and 1914 there were published by myself and my associates1 several studies of the action of diuretics on animals with acute experimental renal lesions. In general, these studies showed that diuretics in acute experimental nephritis were ineffectual or injurious, very often the latter. In 1915 a brief report2 was made of observations on the effect of diuretic drugs in patients with chronic nephritis. In a recent Harvey Lecture3 this same subject is touched on. Here it is pointed out that frequently when the kidney is damaged diuretics do not cause a diuresis, or if a diuresis occurs, there may be evidence of marked renal fatigue subsequent to the diuresis. Skepticism has been expressed as to the efficacy of diuretic drugs in cases of nephritis in which the kidney is seriously damaged. In these several studies theocin was used, as well as other diuretics.