We provide insight into the risk of perioperative thromboembolism and bleeding in patients who have atrial fibrillation, use anticoagulants, and undergo a surgical procedure. Ninety-four patients underwent 121 noncardiac operations during a mean follow-up of 29 months. There was a 3.6-fold increased risk for all bleeding complications within 1 month after surgery compared with the control period (95% confidence interval 1.05 to 12.0). No thromboembolic event occurred in the first month after surgery compared with 11 events in the remaining period (0.4% per month).