Purpose: Tai Chi is an ancient Chinese exercise discipline that uses an integrated mind-body approach to both enhance muscle function, balance, flexibility, and self-efficacy and reduce pain, depression, and anxiety. Thus Tai Chi may be especially suited for the therapy of KOA. Even though several randomized controlled trials have examined the effects of Tai Chi for patients with both knee and hip OA, no systematic quantification of Tai Chi on symptomatic KOA exists. Our aim was to determine the effectiveness of Tai Chi on symptomatic KOA. Methods: A comprehensive and systematic literature search of MEDLINE, Cochrane database, EMBASE and Chinese databases was performed from inception to November of 2011 and used all possible search terms for Tai Chi and osteoarthritis. We also hand searched review articles, manuscripts, and supplements from medical journals for additional studies. We included human randomized controlled trials of Tai Chi for KOA. The outcomes of interest were pain VAS or WOMAC. Study quality was assessed with Jadad criteria assessing randomization, blinding and dropout rates for each study. We computed effect sizes for pain as the standardized mean difference. The effect sizes were pooled using a random effects model. Heterogeneity was assessed using I2 statistic. Results: Our systematic literature search yielded 458 potential relevant studies. Six studies, published between 2000 and 2009, with 382 subjects (80% women) met our inclusion criteria (Table 1). The sample sizes varied between 33 and 152. The mean age was 68 years, and the treatment durations ranged from 8 to 12 weeks. The duration of OA ranged from 6 to 11 years. Three studies used the Yang style, two used the Sun style and one used the Qigong form of Tai Chi. We found a pooled effect size of -0.72 (95%CI -0.97, -0.47) favoring Tai Chi with a heterogeneity score (I2) of 0% (Figure 1). Conclusions: The results from this meta-analysis suggest that Tai Chi training may provide an ideal form of exercise for older individuals with symptomatic KOA. Further studies should be performed to replicate these results and deepen our understanding of this therapeutic modality.