BACKGROUND: Although low-back pain is usually a self-limiting and benign disease that tends to improve spontaneously over time, a large variety of therapeutic interventions are available for its treatment. OBJECTIVES: To assess the effects of acupuncture for the treatment of non-specific low-back pain and dry-needling for myofascial pain syndrome in the low-back region. SEARCH STRATEGY: We updated the searches from 1996 to February 2003 in CENTRAL, MEDLINE, and EMBASE. We also searched the Chinese Cochrane Centre database of clinical trials and Japanese databases to February 2003. SELECTION CRITERIA: Randomized trials of acupuncture (that involves needling) for adults with non-specific (sub)acute or chronic low-back pain, or dry-needling for myofascial pain syndrome in the low-back region. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed methodological quality (using the criteria recommended by the Cochrane Back Review Group) and extracted data. The trials were combined using meta-analyses methods or levels of evidence when the data reported did not allow statistical pooling. MAIN RESULTS: Thirty-five RCTs were included; 20 were published in English, seven in Japanese, five in Chinese and one each in Norwegian, Polish and German. There were only three trials of acupuncture for acute low-back pain. They did not justify firm conclusions, because of small sample sizes and low methodological quality of the studies. For chronic low-back pain there is evidence of pain relief and functional improvement for acupuncture, compared to no treatment or sham therapy. These effects were only observed immediately after the end of the sessions and at short-term follow-up. There is evidence that acupuncture, added to other conventional therapies, relieves pain and improves function better than the conventional therapies alone. However, effects are only small. Dry-needling appears to be a useful adjunct to other therapies for chronic low-back pain. No clear recommendations could be made about the most effective acupuncture technique. AUTHORS' CONCLUSIONS: The data do not allow firm conclusions about the effectiveness of acupuncture for acute low-back pain. For chronic low-back pain, acupuncture is more effective for pain relief and functional improvement than no treatment or sham treatment immediately after treatment and in the short-term only. Acupuncture is not more effective than other conventional and "alternative" treatments. The data suggest that acupuncture and dry-needling may be useful adjuncts to other therapies for chronic low-back pain. Because most of the studies were of lower methodological quality, there certainly is a further need for higher quality trials in this area.