Objective To compare the efficiency of original neuromyelitis optica(NMO)-IgG assay of detecting NMO-IgG with a new anti-aquaporin-4(AQP4)assay of detecting AQP4,and to explore the accuracy of the method in the diagnosis of NMO and multiple sclerosis(MS).Methods The sera were obtained from 44 patients with NMO and 46 patients with MS and were tested by both NMO-IgG and antiAOP4 assays.NMO-IgG was identified by original NMO-IgG assay with a substrate from mouse brain.AntiAQIP4 was detected by anti-AQP4 antibody assay.The results from the two assays were statistically analyzed to compare accuracy and specificity of the methods.Results The results of the two assays were concordant in 45 testing negative cases and 36 positive cases(Kappa=0.798.P=0.000).The McNemar test showed that the positive rate of the two assays were not significantly different(P=1.000).The NMO-IgG assay showed 77.3% sensitivity,87% specificity,82.2% diagnosis accuracy,85%positive predictive value,87% negative predictive value.and 74.3%Younden index. The anti-AOP4 antibody assay showed 88.6% sensitivity,95.7%specificity,92.2% diagnosis accuracy,98.1% positive predictive value,89.8% negative predictive value.and 84.3% Younden index.Conclusions This study demonstrated that NMO-IgG and AQP4 antibody detection have high sensitivity and specificity to detect NMO and MS.Anti-AQP4 detected by anti-AQP4 antibody assay may be more useful for NMO diagnosis.