The occurrence of azotemia in the absence of nephritis is recognized and has been discussed extensively in the literature. Little attention, however, has been paid to the possibility of nitrogen retention in the blood being due primarily to anuria resulting from hypotension. Both Roch1and Merklen2in their papers on the subject call attention to anuria or oliguria as a frequent extrarenal cause of azotemia, but they do not mention hypotension among the causes for this oliguria. Azotemia due to hypotension appears to be a rare occurrence, or else blood studies with this point in mind have not been made in cases of marked hypotension. It seems probable that the latter is the case. Studies3on the physiology of the kidney have shown that in the experimental animal a minimum blood pressure of from 30 to 40 mm. of mercury is necessary for the secretion of urine.