AIM: Irritable bowel syndrome (IBS) is a common disorder and many patients fail to find adequate relief from conventional therapies for their symptoms. This study tests the claim that acupuncture is effective for a majority of these patients.METNODS: A prospective, blinded, sham acupuncturecontrolled trial of traditional Chinese acupuncture was performed at a single postgraduate teaching hospital in Europe. Sixty patients with well-established IBS were recruited. The blinded comparator was sham acupuncture administered by the second of two acupuncturists who alone was aware of the randomization, and who otherwise followed the prescription of the first. The primary endpoint was a defined fall in the symptom score at 13 wk (by intention to treat). The prior expectation was a 30%placebo response, and a response rate of 70% from acupuncture, for which the study was adequately powered.RESULTS: Patients in treated and sham groups improved significantly during the study-mean improvement in scores being equal (minus 1.9) and significant for both (P＜0.05;one-tailed t test). There was a small numeric but nonsignificant difference between the response rate in patients receiving acupuncture (40.7%) and sham treatment (31.2%). Several secondary end-points marginally favored active treatment, but an improved symptom score of any degree of magnitude occurred more often with sham therapy (65.6% vs 59.2%). For no criterion was statistical significance approached.CONCLUSION: Traditional Chinese acupuncture is relatively ineffective in IBS in the European hospital setting,and the magnitude of any effect appears insufficient to warrant investment in acupuncture services.