ObjectiveTo explore the diagnostic value of fractional exhaled nitric oxide (FeNO) in adult asthma.MethodsPubMed, Embase, Cochrane Library, Wanfang, CNKI and VIP databases were searched for relevant literatures from the time of database establishment to February 2021. Data analysis were made by Revman and Stata.ResultsA total of 44 articles with 47 records and 9654 subjects were included. The diagnosis sensitivity, specificity, positive and negative predictive value of FeNO were 0.71 (95%CI 0.65 - 0.76), 0.80 (95%CI 0.75 - 0.84), 3.47 (95%CI 2.86 - 4.21), and 0.37 (95%CI 0.31 - 0.43), respectively. The diagnostic odds ratio was 9.49 (95%CI 7.13 - 12.61), and the area under the receiver operating characteristic curve was 0.82 (95%CI 0.79 - 0.85).ConclusionsFeNO has certain diagnostic value in diagnosis of asthma. Types of asthma, region and cut-off value all have impact on the diagnostic efficiency of FeNO.