Objective To review literatures regarding the diagnosis of asthma with the measurement of exhaled nitric oxide( eNO) and assess the effectiveness and accuracy of eNO in the diagnosis of asthma.Methods MEDLINE, OVID, CBMdisc, CNKI( 1991 to 2008) for studies involving the diagnostic value of eNO were searched, and references of included studies were also hand searched. QUADAS ( Quality Assessment of Diagnostic Accuracy Studies) items were used for quality assessment in the systematic review. Meta-disc software was used to analyze heterogeneity. Sensitivity, specificity and summary diagnostic odds ratio( SDOR) were used for the pooled analysis. The summary receiver operating characteristic ( SROC)curves were drew and the summary areas under the SROC ( SAUC) were calculated. Finally, sensitivity analysis was performed. Results Eleven literatures with15 studies were included. These 15 studies had well controlled the bias of partial verification, differential verification, incorporation and withdrawals. The possibility of the disease progression bias was less and the reference standard review could have a greater bias. The spectrumcomposition of a study, the inclusion and exclusion criteria and the reporting quality were poorly reported. In statistical analysis, the totally pooled sensitivity, pooled specificity, SDOR, SAUC of the measurement of eNO in the diagnosis of asthma was 0. 68, 0. 79, 12. 73, 0. 8446, respectively. Sensitivity analysis demonstrated no disproportionate influences of individual study. Conclusions eNO has a certain value in the diagnosis of asthma. To make further analysis, more studies with high quality are needed.