OBJECTIVES: Acupuncture has been used as a therapy for various gastrointestinal disorders, including irritable bowel syndrome (IBS). However, there is scant information on the effect of acupuncture on gut physiology. The purpose of this study was to evaluate the effect of transcutaneous electrical acustimulation (TEAS) on rectal tone, compliance and perception in IBS patients. METHODS: Seven patients with diarrhea-predominant IBS were studied during control, sham stimulation and acupoints (ST36 and P6) stimulation periods. Rectal tone, compliance and perception to rectal balloon distension were assessed with a barostat apparatus. RESULTS: Acustimulation at ST36 and P6, but not sham stimulation, significantly increased the threshold of rectal sensation of gas, desire to defecate and pain, as compared to control period. However, rectal tone and compliance were not significantly affected during TEAS. CONCLUSIONS: TEAS, at the above acupoints, can reduce rectal sensitivity in IBS patients. The effect is not modulated by changes in rectal biomechanics.