Nonvalvular atrial fibrillation (NVAF) is the most common arrhythmia. It is of a high disability and death rate, and seriously affects quality of life. Although New oral anticoagulants (NOACs) are recommended for anticoagulation therapy of atrial fibrillation, they are not widely used for the high cost and limited availability. Warfarin is effective and economical. The risk of thromboembolism and anticoagulant hemorrhage is higher in patients >65 years with NVAF. So, it is of great clinical significance to explore the optimal anticoagulation intensity of warfarin in patients >65 years of China, and other ethnicities. Some studies suggested that low-intensity international normalized ratio (INR) has similar antithrombotic efficacy comparing to standard-intensity INR, whereas bleeding risk was significantly reduced. But others showed conflicting results. We pooled the efficacy and safety data of low- and standard-intensity warfarin therapy for patients over 65 years with NVAF by meta-analysis, as to evaluate optimal INR intensity of warfarin therapy in patients over 65 years. We identified 18 studies providing data of 2105 patients receiving anticoagulation therapy with warfarin. On meta-analysis (odds ratio [OR] [95% confidence interval {CI}]), low-intensity INR conferred similar efficacy to standard intensity INR on all thrombosis (1.28 [0.90 to 1.81]), stroke (1.09 [0.67 to 1.77]), other thromboembolism ([peripheral and pulmonary embolism] 2.26 [0.89 to 5.79]), and all cause death (1.38 [0.94 to 2.02]). Low-intensity INR conferred better safety profile than standard intensity INR in major bleeding (intracranial and gastrointestinal hemorrhage) (0.32 [0.19 to 0.52]), minor bleeding (gum, nasal cavity and conjunctival hemorrhage, skin ecchymosis, hematuria, hemoptysis) (0.30 [0.20 to 0.45]), and all bleeding (0.30 [0.22 to 0.40]). In conclusion, low-intensity INR (1.5 to 2.0) of warfarin therapy is as effective as standard intensity INR (2.0 to 3.0) therapy in reducing thromboembolic risk in patients>65 years with NVAF, and has a safer profile of bleeding. © 2020 Elsevier Inc.