In children, pyuria of long duration is associated frequently with organic changes and congenital anomalies in the kidneys, ureters, bladder or urethra. Such an organic basis for the development of pyuria has been pointed out in several series of cases, notably those of Beer,1 Hyman,2 Lowsley and Butterfield,3 Smith,4 Mixter,5 and Helmholz.6 The final diagnosis has usually rested on urologic investigation by means of the cystoscope. Direct examination is thus made of the urethra and bladder; and roentgenograms of the ureters and pelves of the kidneys are made following ureteral catheterization. But such instrumental examination is not without danger. Many children are not in a condition to undergo the trauma of cystoscopy with its not infrequent reaction, nor are they even suitable patients for general anesthesia, a necessary part of the urologic examination of young children. The difficulty of the procedure and the frequency