BACKGROUND: The effectiveness of acupuncture in primary dysmenorrhoea is not fully understood. OBJECTIVES: To assess the effectiveness of acupuncture for the symptomatic treatment of primary dysmenorrhoea from randomised controlled trials (RCTs). SEARCH STRATEGY: Nineteen electronic databases, including English, Korean, Japanese and Chinese databases, were systematically searched for RCTs investigating acupuncture for primary dysmenorrhoea up to July 2008 with no language restrictions. SELECTION CRITERIA: All RCTs that evaluated the effects of acupuncture compared with controls were included. Studies that assessed the effect of moxibustion or body acupressure were excluded. DATA COLLECTION AND ANALYSIS: The study abstraction and quality assessment of all studies were undertaken following the detailed descriptions of these categories as described in the Cochrane Handbook for Systematic Reviews of Interventions. MAIN RESULTS: Twenty-seven RCTs were systematically reviewed. Only nine of the 27 trials clearly described their methods of randomisation and none of the trials stated the methods of allocation concealment. Compared with pharmacological treatment or herbal medicine, acupuncture was associated with a significant reduction in pain. Three studies reported reduced pain within groups from baseline; however, two RCTs did not find a significant difference between acupuncture and sham acupuncture. AUTHOR'S CONCLUSIONS: The review found promising evidence in the form of RCTs for the use of acupuncture in the treatment of primary dysmenorrhoea compared with pharmacological treatment or herbal medicine. However, the results were limited by methodological flaws. The evidence for the effectiveness of acupuncture for the treatment of primary dysmenorrhoea is not convincing compared with sham acupuncture. Further rigorous nonpenetrating placebo-controlled RCTs are warranted.