OBJECTIVE To explore the condition of the cellular immune function of children with obstructive sleep apnea hypopnea syndrome(OSAHS) and its change after operation METHODS Eighty children diagnosed as OSAHS were included in this study. T lymphocyte subsets and NK cells of the blood were measured before operation and one month after operation respectively. Children without the related disorders or systemic disease were recruited as control group.RESULTS Before operation, CD4+T cell percentage, CD4+/CD8+ ratio and NK cell percentage in OSAHS children were significantly lower than that in the control group[(26.19±3.38)%vs (5.10±4.09)%, (0.90±0.19)%vs (1.61±0.52)%, (11.45±4.35)%vs (13.73±3.78)%,P<0.05], CD8+T cell percentage was significantly higher than that in the control group[(30.02±5.50)%vs (22.31±3.42) %,P<0.05]. The difference, between the two groups, in CD3+T cells was not statistically significant. After operation, the CD4+T cells, CD8+T cells, CD4+/CD8+ ratio, the percentage of NK cells and CD3+T cells showed no significance difference compared with that before operation (P>0.05). CONCLUSION OSAHS may damage the cellular immune function. The operation does not reduce the cellular immune function in the short term.