The retroperitoneal structures are protected by the vertebral column and erector spinal muscles behind and buffered by the abdominal contents in front. This anatomical position makes physical examination difficult and impedes the detection of pathology. Many pathological processes are detected by their effect upon the morphology or function of the urinary tract. Ureteral obstruction or displacement occurs readily due to the delicate structure of this organ and its loose attachment to adjacent structures. An obstructive uropathy may be the first evidence of retroperitoneal neoplastic process. Alternately, gastrointestinal symptoms may herald hydronephrosis. In the female, changes in the pelvic organs frequently affect the urinary tract, for example, the hydronephrosis of pregnancy. The detection and elucidation of pathology in the retroperitoneum calls for clinical acumen and the utilization of many diagnostic and radiographic techniques.