The renin-angiotensin-aldosterone system (RAAS) has emerged as an important hormonal system in the initiation and pathogenesis of atrial fibrillation (AF). Therefore, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) are emerging as novel drugs for the prevention of AF. A meta-analysis of 11 randomized, controlled, parallel-design clinical trials evaluating effect of ACEIs or ARBs on the development of AF was performed. Treatment with ACEIs or ARBs reduced the relative risk (RR) of AF in patients with hypertension by 23% [RR 0.769, P < 0.001, 95% confidence interval (CI) 0.686-0.862] and by 11% in patients after myocardial infarction (RR 0.898, P < 0.05, 95% CI 0.814-0.992). Reduction in AF was greatest in patients after electrical cardioversion (RR 0.491, P < 0.001, 95% CI 0.334-0.720) and in patients with heart failure (RR 0.684, P < 0.001, 95% CI 0.594-0.787). Overall, inhibition of the RAAS reduced the RR of AF by 19% (RR 0.810, P < 0.001, 95% CI 0.759-0.865).