Objectives: To review the available evidence on the effectiveness of acupuncture in the treatment of low back pain. Data Sources:MEDLINE, National Guideline Clearinghouse, Guidelines Finder, Cochrane Library, DARE, Bandolier, UpToDate and Index of Portuguese Medical Magazines. Review Methods: Research using the MeSH terms acupuncture and low back pain and the DeCS terms acupuntura e dor lombar. The search was limited to articles published between January 2000 and May 2009 in english, portuguese and spanish. American Family Physicians Strength of Recommendation Taxonomy (SORT) was used to assess the level of evidence. Results: Two meta-analysis, six systematic reviews, three randomised controlled trials and three guidelines met inclusion criteria. Guidelines say that acupuncture might be helpful in the treatment of low back pain. Unspecific chronic low back pain: the meta-analysis, systematic reviews and randomised controlled trials demonstrated that acupuncture is more effective than notreatment and that the association of acupuncture with conventional treatment is more effective than isolated conventional treatment. The studies didnt demonstrate that acupuncture was more effective than placebo or conventional therapies. Acute low back pain: data are inconclusive. Conclusions: Acupuncture is effective in the treatment of unspecific chronic low back pain, isolated or in addition to other interventions (SORT A); it was not proved that acupuncture was superior to other interventions. In the treatment of acute low back pain, there was no evidence of effectiveness of acupuncture. It would be advisable to do high quality, long-term, controlled and randomised studies, addressing its cost-benefit.