We evaluated the effect of acupuncture stimulation on the urine jet phenomenon in humans by color Doppler ultrasonography. Twenty healthy volunteer subjects (10 men and 10 women) aged 18 to 26 (mean, 23) years drank 350 ml of water 3 hours before the experiment started and were then directed to restrict eating and drinking. Ultrasonographic images showing the bladder in transverse section enabled us to observe the urine jet phenomenon. The frequency of the appearance of the jet phenomenon was counted for a period of 5-minutes, and the maximum velocity and duration of the phenomenon were measured. Blood flow in the renal interlobar arteries was also studied to measure the resistance index in order to assess renal blood flow. Acupuncture needles were inserted at the Chung-Chi (CV3) acupoint, where electroacupuncture and manual stimulation were performed. No stimulation was used on the control group. Frequency of appearance and maximum velocity of the urine jet increased in both the electroacupuncture and manual stimulation groups, but not in the control group. Duration of the phenomenon was shorter with both types of stimulation, but was longer in the control group than the baseline duration time. Resistance index did not change significantly in any group. We conclude that acupuncture stimulation affects ureter function and promotes its peristalsis.