Objective To provide assistance for the diagnosis, treatment and evaluation of illness state via detecting the level of nitric oxide (NO) in airways of patients with persistent allergic rhinitis (PAR). 〖WTHZ〗Methods NO concentrations were detected with NIOX analysis system in upper and lower airways of 67 PAR patients. Of them, 28 cases were mild and 39 were moderate to severe. 30 healthy adults were chosen as control. The pulmonary function was measured with Pony FX analysis system. Results ① The NO concentrations of upper airway of PAR group and the control group were (88.4±3.5) ppb and (84.2±2.6) ppb respectively, and the difference was statistically insignificant (P>0.005). ② The NO concentration of lower airway in PAR group was (44.2±3.6) ppb, which was much higher than that of the control group (15.7±5.2) ppb with statistically significant difference (P=0.000). ③ In the PAR group, the NO concentrations of lower airway in the mild subgroup and moderate to severe subgroup were (22.7±9.9) ppb and (59.7±4.0) ppb respectively, and the difference was statistically significant (P=0.000). ④ There was no correlation between NO concentrations of upper and lower airway in PAR group. Conclusion With advantage of convenient and prompt monitoring the inflammatory degree of lower airway in PAR, concentration of lower airway NO may be used as an index for the management and treatment of PAR patients who have no symptoms of lower respiratory inflammation with normal pulmonary function but with increased lower airway NO concentration. Further study is required on the significance of upper airway NO measurement in estimating airway inflammation of AR.