Objectives: In this study, we tested the hypothesis that pulmonary artery venting would decrease the incidence of atrial fibrillation after coronary artery bypass surgery. Methods: This prospective study included 301 patients who underwent complete myocardial revascularization with cardiopulmonary bypass in our department during a 2-year period. The patients were randomly divided into 2 groups: group I included 151 patients who underwent aortic root venting and group II included 150 patients who underwent pulmonary arterial venting for decompression of the left heart. Pre-, peri-, and postoperative risk factors for atrial fibrillation were assessed in both groups. Results: The mean age was similar in the 2 groups. The mean number of anastomoses was significantly higher in group I (2.8 ± 0.8) than in group II (2.4 ± 0.8) (P = 0.001). The mean cross-clamp time was 42.7 ± 17.4 minutes in group I and 54.1 ± 23.8 minutes in group II (P = 0.001). The mean cardiopulmonary bypass time was 66.4 ± 46.1 minutes in group I and 77.4 ± 28.6 minutes in group II (P = 0.08). The incidence of atrial fibrillation was 14.5% (n = 21) in group I and 6.5% (n = 10) in group II (P = 0.02). Multivariate regression analysis showed that pulmonary artery venting decreased the postoperative incidence of atrial fibrillation by 17.6%. Conclusions: Pulmonary arterial venting may be used as an alternative to aortic root venting during on-pump coronary bypass surgery, especially in patients at high risk of postoperative atrial fibrillation. © 2013 Forum Multimedia Publishing, LLC.