Five TNF- inhibitors including adalimumab (ADA, Humira, Abbvie Inc., Chicago, IL), etanercept (ETN, Enbrel, Immunex, Thousand Oaks, CA), golimumab (GOL, Simponi, Janssen Biotech Inc., Malvern, PA), certolizumab (CZP, Cimzia, UCB Pharma, Brussels, Belgium), and infliximab (IFX, Remicade, Janssen Biotech Inc., Malvern, PA) have been developed to target TNF- and alleviate joint swelling, pain, and inflammation in AS patients. Through different mechanisms 5 drugs affect the function of TNF-. be a promising treatment for AS, but carries an increased incidence rate of adverse events and injection-site reaction. Conclusion: Due to the existence of the unstable factors, further studies need to be done to verify the result of this study. Keywords: ankylosing spondylitis, meta-analysis, randomized controlled trials, tumor necrosis factor-alpha inhibitors 1.?Introduction As a chronic inflammatory disease, ankylosing spondylitis (AS) affects the axial skeleton and also the peripheral joints and nonarticular structures to a varying degree. AS is a prototype of an interrelated group of disorders called spondyloarthropathies (SpAs). AS is more common in men than women, with a ratio of approximately 2C3:1. The common features of AS are: restrictions in spine movements, chronic inflammatory back pain, spondylitis, and sacroiliitis; early symptoms of AS are recognized in teenagers or in young adults. The prevalence of AS is 0.52% to 0.55% in the USA and 0.3% in China.[1C3] AS is progressive inflammatory disease, leading to a large number of people with functional limit and impact on the daily activities of patients. The goals of treatment of AS are to alleviate symptoms (stiffness, pain, and joint swelling), improve body function, and delay or avoid structural damage, resulting in physical damage and deformity. AS is currently managed through a multidisciplinary approach that involves exercise, physiotherapy, and drug therapy.[5,6] Nonsteroidal anti-inflammatory drugs (NSAIDs) are the mainstay of AS therapy, reducing the stiffness and pain of inflammation. However, at least one-third of the patients were less responsive to NSAID treatment or severe side effects, and therefore need disease control drugs, in addition to improving symptoms treatment.[7,8] The drug’s safety and effectiveness must meet the requirements of US Food and Drug Administration (FDA) that has determined Histone Acetyltransferase Inhibitor II that a drug produces the benefits it is supposed to without causing side effects that would outweigh the benefits. When analyzing the safety of a drug, it is essential to determine how to inform adverse events (AEs) and so the safety profile known. The approval of a drug as a treatment by the drugs regulatory agencies, such as the FDA and European Medicines Agency (EMA), is usually based on the results of clinical trials. An alternative approach to analyzing the safety profile is meta-analyses, which combine the results of clinical trials in order to analyze a large number of patients exposed to the biological agent. Tumor necrosis factor-alpha (TNF-) is a multifunctional cytokine in the course of disease as previous studies found abundant levels of TNF- in IkBKA the sacroiliac joint of AS patients.[11,12] TNF- inhibitors, adalimumab, etanercept, certolizumab, golimumab, and infliximab have proved to be effective treatment options for patients with AS.[13C15] According to the meta-analysis, adalimumab, Histone Acetyltransferase Inhibitor II etanercept, and infliximab showed similar effects on reducing signs and symptoms of AS. However, the results for the safety of TNF- inhibitors in the treatment of AS were not consistent. Therefore, the safety of TNF- inhibitors for the treatment of AS should be systematically evaluated. Here in this study, we performed a meta-analysis Histone Acetyltransferase Inhibitor II of eligible studies to assess the safety of TNF- inhibitors (adalimumab, infliximab, etanercept, certolizumab, and golimumab) in patients with AS. 2.?Materials and methods As this study is a meta-analysis of data in the literatures, the ethical approval was waived. 2.1. Search strategy To perform this meta-analysis, we conducted a structured search in PubMed (ncbi.nlm.nih.gov/pubmed) and EMBASE (http://www.embase.com) databases up to November 2015.