Background: Renin-angiotensin system (RAS) plays an important role in atrial fibrillation (AF). Recently, many publications have studied the associations between RAS-related gene polymorphisms and AF risk, with inconsistent results. To further evaluate these associations, we carried out a meta-analysis of all the published studies. Methods: Electronic searches were used to identify published studies evaluating RAS-related gene polymorphisms and AF risk before April 2009. We extracted data sets and performed meta-analysis with standardized methods. Results: A meta-analysis of 12 publications on association between angiotensin-converting enzyme (ACE insertion/deletion) and AF risk was performed. The pooled relative risk (RR) of allele D versus I was 1.19 (95% CI, 1.07-1.32, P < .01), pooled RR of DD and DI versus II was 1.31(95% CI, 1.09-1.58, P < .01) and 1.06 (95% CI, 0.97-1.16, P = .22) respectively. In subgroup analysis, a stronger association was found in hypertensive population, Western ethnic, lone AF, and patients aged ≥65 years, with pooled RR of DD versus II was 1.74 (95% CI, 1.39-2.18, P < .01), 1.27 (95% CI, 1.01-1.59, P = .04), 1.53 (95% CI, 1.31-1.78, P < .01) and 1.38 (95% CI, 1.10-1.73, P < .01), respectively. Conclusion: The results suggested an association between ACE insertion/deletion and AF risk. More large-scale studies are warranted to document the conclusive evidence of the effects of the RAS genes on AF risk. © 2010 Mosby, Inc. All rights reserved.