Introduction : Postoperative atrial fibrillation (POAF) is one of the most common complications after cardiac surgery. Patients who develop POAF have a prolonged stay in the intensive care unit and hospital and an increased risk of postoperative stroke. Many guidelines for the management of cardiac surgery patients, therefore, recommend perioperative administration of beta-blockers to prevent and treat POAF. Landiolol is an ultra-short acting beta-blocker, and some randomized controlled trials of landiolol administration for the prevention of POAF have been conducted in Japan. This meta-analysis evaluated the effectiveness of landiolol administration for the prevention of POAF after cardiac surgery. ; Methods : The Medline/PubMed and BioMed Central databases were searched for randomized controlled trials comparing cardiac surgery patients who received perioperative landiolol with a control group (saline administration, no drug administration, or other treatment). Two independent reviewers selected the studies for inclusion. Data regarding POAF and safety outcomes were extracted. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using the Mantel–Haenszel method (fixed effects model). ; Results : Six trials with a total of 560 patients were included in the meta-analysis. Landiolol administration significantly reduced the incidence of POAF after cardiac surgery (OR 0.26, 95% CI 0.17–0.40). The effectiveness of landiolol administration was similar in three groups: all patients who underwent coronary artery bypass grafting (CABG) (OR 0.27, 95% CI 0.17–0.43), patients who underwent CABG compared with a control group who received saline or nothing (OR 0.28, 95% CI 0.17–0.45), and all patients who underwent cardiac surgery compared with a control group who received saline or nothing (OR 0.27, 95% CI 0.17–0.42). Only two adverse events associated with landiolol administration were observed (2/302, 0.7%): hypotension in one patient and asthma in one patient. ; Conclusion : Landiolol administration reduces the incidence of POAF after cardiac surgery and is well tolerated.