A new, sensitive technique for recording intraureteral pressure was used to investigate the effects of spinal anaesthesia, lidocaine, and morphine on ureteral peristalsis in 21 female patients. Spinal anaesthesia, comprising the segments up to ThX-Th III, did not affect ureteral motility, nor did morphine given intravenously in a 15 mg dose. Four to 8 ml 4% lidocaine injected into the renal pelvis, after an initial, brief period of stimulation, markedly reduced ureteral peristalsis. Normal ureteral activity returned within 15-30 min. It is concluded that the activity in extraneous autonomous nerves is of minor importance for ureteral peristalsis, and that morphine, in doses used clinically, does not affect ureteral motility.