AIM:To measure the concentration of nitric oxide (NO) in serum and aqueous humor of the peseudoexfoliation glaucoma (PEG) patients and to study its possible role in the pathogenesis of PEG.METHODS:The NO concentration in serum and aqueous humor of PEG patients (experimental group) and cataract patients(control group) was detected by nitric acid reductase method.RESULTS:The NO level in serum and aqueous humorin experimental group were obviously lower than that of in control group (P<0.01) .CONCLUSION:The decrease of NO concentration in serum and aqueous humor of PEG patients may be one of reasons of filtration resistomce increase.