BACKGROUND: Acupuncture is commonly used in treating insomnia in China, and clinical studies have shown that acupuncture may have a beneficial effect on insomnia compared with Western medication. METHODS: We included randomized controlled trials on acupuncture for insomnia. We searched PubMed, the Cochrane Library (2008 Issue 3), China Network Knowledge Infrastructure (CNKI), Chinese Scientific Journal Database (VIP), and Wan Fang Database. All searches ended in December 2008. Two authors extracted data and assessed the trials’ quality independently. RevMan 5.0.17 software was used for data analysis with effect estimate presented as relative risk (RR) and mean difference (MD) with a 95% confidence interval (CI). RESULTS: Forty-six (46) randomized trials involving 3811 patients were included, and the methodological quality of trials was generally fair in terms of randomization, blinding, and intention-to-treat analysis. Meta-analyses showed a beneficial effect of acupuncture compared with no treatment (MD -3.28, 95% CI -6.10 to -0.46, p = 0.02; 4 trials) and real acupressure compared with sham acupressure (MD -2.94, 95% CI -5.77 to -0.11, p = 0.04; 2 trials) on total scores of Pittsburgh Sleep Quality Index. Acupuncture was superior to medications regarding the number of patients with total sleep duration increased for >3 hours (RR 1.53, 95% CI 1.24-1.88, p < 0.0001). However, there was no difference between acupuncture and medications in average sleep duration (MD -0.06, 95% CI -0.30-0.18, p = 0.63). Acupuncture plus medications showed better effect than medications alone on total sleep duration (MD 1.09, 95% CI 0.56-1.61, p < 0.0001). Similarly, acupuncture plus herbs was significantly better than herbs alone on increase of sleep rates (RR 1.67, 95% CI 1.12-2.50, p = 0.01). There were no serious adverse effects with related to acupuncture treatment in the included trials. CONCLUSIONS: Acupuncture appears to be effective in treatment of insomnia. However, further large, rigorous designed trials are warranted.