ObjectiveTo investigate the impact of longterm nasal irrigation (NI) on the function of immunological defense in normal nasal mucosa.Methods55 healthy volunteers completed the study. They were randomly divided into 2 groups, normal saline irrigation (NSI) group and hypertonic saline irrigation (HSI) group. The NSI group mean included 29 volunteers (male 13，female 16), age ranged from 18 to 61 years old with an average of 37.90, and those of the HIS group were 26(male 13，female 13) with an average of 40.65 (ranged from 18 to 66). Patients of the NSI group received NI using 0.9% saline and those of the HSI group with 3% saline with a temperature of 40°C, once a day, half an hour before sleeping in the evening. The total period of intervention was 3 months (90 days). The concentrations of lysozyme (LYSO), lactoferrin (LF), surfactant protein (SP) A and secretory immunoglobulin (SIg) A in nasal lavage fluid (NLF) from the two groups were examined before and after intervention of NI.ResultsThere were no statistical differences between NSI and HSI groups in sex, age, and contents of LYSO, LF, SPA and SIgA in NLF before NI. The concentrations of these four proteins were not changed significantly after NSI and HSI treatment. In addition, there were no significant differences in these substance expressions in NLF between these two groups after the NI intervention.ConclusionLongterm NI treatment may not have harmful effect on the immune barrier of normal nasal mucosa.