This report deals with the histologic and gross anatomy of the upper urinary tract (calyces, pelvis, and ureter) as well as the nerve supply to this region. It also covers the physiological transport of urine from the kidneys to the bladder, which is reviewed on the basis of experimental and clinical studies. A pacemaker system present in the proximal calyces has been found to have an important physiological role in urine transport. However, clinical experience has shown that urine transport is not affected by surgery such as pyeloplasty and pyelolithotomy which impairs the activity of this pacemaker. Electron microscopic and histochemical studies as well as the maintenance of urine transport after renal grafting suggest that the nerve supply to the upper urinary tract is not dominant in regard to this function. This study also investigated urinary transportation in the presence of urinary tract obstruction due to various diseases, and demonstrated that urine is also conveyed by gravity and not solely by ureteric peristalsis. The use of internal stenting and percutaneous urinary diversion thus appears to be reasonable. Although the detailed etiology congenital hydronephrosis is still unknown, there is no doubt that it involves dysfunction of the ureteropelvic junction, since urine transport is improved by the endoscopic or surgical formation of a physiological tunnel at this junction which can regulate the volume of urine transported according to urine output. It is important for studies of upper urinary tract function to be conducted in close relation to clinical practice and not to simply be confined to esoteric experimental situations.