Abstract:[Objective] To explore whether body mass index (BMI) is associated with adverse events after shoulder arthroplasty. [Methods] The published papers about the relationship between obesity and shoulder arthroplasty were searched from databases, such as PubMed, EMBASE, Web of Science and Cochrane in English, as well as Wanfang, CNKI and VIP in Chinese. The quality of the literatures was evaluated by Newcastle Ottawa scale (NOS) , and the data of the included literatures were extracted. Revman 5.3 software provided by Cochrane Collaboration Network was used for a meta-analysis. [Results] A total of 10 literatures were included, with sample size in each study ranged from 76 to 144139. All the studies were enrolled as observational studies, including 3 prospective studies and 7 retrospective studies, which all proved of high-quality. As results of the meta-analysis, the obesity (BMI>30 kg/m2 ) had significantly higher postoperative infection rate [OR=3.83, 95% CI (2.72~5.41) , I 2 =64% ] , significantly higher incidence of venous thrombosis [OR=3.93, 95% CI (3.61~ 4.29) ] , while the overweight (BMI>25kg/m2 ) consumed significantly longer operation time [MD=6.90, 95%CI (3.79~10.00) , I 2 =0%] . How- ever, there were no significant differences between the overweight patients and the normal weight patients in terms of postoperative compli- cations [OR=0.87, 95%CI (0.71~1.08) , I 2 =38%] , postoperative revision rates [OR=1.48, 95%CI (1.39~1.57) , I2 =71%] , hospitalization time [MD=0.03, 95%CI (-0.03~0.09) , I 2 =1%] and American Shoulder and Elbow Surgeon (ASE) scores [MD=0.36, 95%CI (-7.38~8.11) , I 2 =0%] . [Conclusion] The obesity has considerably higher risk of infection and takes significantly longer operation time, However, all pa- tients do get benefit from shoulder arthroplasty.