The term “nonfunctioning#x201D; kidney is commonly used to describe the non-visualized kidney after the intravenous injection of contrast material. As the urologist appreciates, urine at times can be observed coming from this kidney, and the intravenously injected dyes, methylene blue and indigo carmine, may be seen issuing from the ureteric orifice. In addition, with large quantities of opaque medium, the radiologist may visualize the renal substance and/or the collecting system. Although a considerable amount of attention has been given to bilateral poor visualization of the kidneys in patients with impaired renal function, little interest has been shown in the nonvisualized kidney, other than the identification of the dilated urinary tract (8). After the lack of visualization with the recommended 25 cc dose of contrast material, a common procedure has been to double the dose, and the term“double-dose intravenous pyelography” thus came into use. This technic led to the diagnosis of the cause of an obstr...