OBJECTIVES: To evaluate the efficacy of yoga as an intervention for chronic low back pain (CLBP) using a meta-analytical approach. Randomized controlled trials (RCTs) that examined pain and?or functional disability as treatment outcomes were included. Post-treatment and follow-up outcomes were assessed. METHODS: A comprehensive search of relevant electronic databases, from the time of their inception until November 2011, was conducted. Cohen's d effect sizes were calculated and entered in a random-effects model. RESULTS: Eight RCTs met the criteria for inclusion (eight assessing functional disability and five assessing pain) and involved a total of 743 patients. At post-treatment, yoga had a medium to large effect on functional disability (d=0.645) and pain (d=0.623). Despite a wide range of yoga styles and treatment durations, heterogeneity in post-treatment effect sizes was low. Follow-up effect sizes for functional disability and pain were smaller, but remained significant (d=0.397 and d=0.486, respectively); however, there was a moderate to high level of variability in these effect sizes. DISCUSSION: The results of the present study indicate that yoga may be an efficacious adjunctive treatment for CLBP. The strongest and most consistent evidence emerged for the short-term benefits of yoga on functional disability. However, before any definitive conclusions can be drawn, there are a number of methodological concerns that need to be addressed. In particular, it is recommended that future RCTs include an active control group to determine whether yoga has specific treatment effects and whether yoga offers any advantages over traditional exercise programs and other alternative therapies for CLBP.