Increased arterial blood pressure occurs in patients having a variety of diseases. Some of these diseases can be demonstrated clinically by pyelography, and because of this fact pyelography is included in the routine study of hypertensive patients in the University of Michigan Hospital. Patients with hypertension also have electrocardiographic study, eyeground examination, orthodiagraphic study and study of total renal function. When the excretory urograms are unsatisfactory for diagnosis, cystoscopy with split phenolsulfonphthalein and retrograde pyelogram is done. During the years 1940 to 1945 inclusive, 2,055 hypertensive patients were studied in the urologic clinic(table 1). This figure represents approximately 20 percent of the total number of pyelograms (9,501) that were made during the six year period covered by this study. Over-all, there was an incidence of renal abnormalities of 8.9 per cent. It will be noted that in 1940 and 1941 there was an incidence of 15.1 per cent, as against 5.1 per cent in 1945. This means that the interpretation of the pyelogram in the early part of the