Once urology was established as a medical specialty, the initial anatomic-morpho­ logical point of view was soon supplemented by functional considerations and diagnostic procedures, thanks to the introduction of the cystoscope (NrTzE, 1877) and retrograde pyelography (VOELCKER, ]OSEPH and VON LrCHTENBERG, 1903). Intravenous urography (VOLKMANN, 1924; VON LrCHTENBERG, PFLAUMER and SWICK, 1929) lent roentgen examinations a more functional aspect. The word "urodynamics" refers to the functional approach to the urinary trac- from the renal pelvis and calyces, the ureter and bladder down to the bladder neck and urethra. The embryologically denned topographie regions of the urogenital tract are peripheral relays, while the actual site of action of both normal and patho­ logical urodynamics is to be found in the various hollow muscular organs. Despite extensive basic research and much knowledge acquired in this neld, the active transport system between site of production and storage, i. e. the renal pelvis and ureter, is still regarded in clinical practice mainly from the anatomic-morphological viewpoint. It is not easy to obtain adequate information for the clinical assessment of functional disturbances of the ureter. For instance, retrograde exploration methods may often be complicated by infection. Clinically applicable methods for functional assessment of the upper urinary tract are (RUTISHAUSER): direct observation of the ureteral orinces, intravenous and retro­ grade visualization by roentgen contrast medium, sequential pyelography, roentgen kymography, and cinematography. Such methods allow good functional exploration by an experienced investigator but they yield hardly any objectively reproducible records.