Abstract: Objective: To study the effect of azithromycin on immune function of children with mycoplasma pneumoniae pneumonia. Methods: One hundred and ten children with mycoplasma pneumoniae pneumonia were randomly divided into observation group and control group(n=55) according to the digital table method. Children in observation group were given azithromycin at 10 mg·kg^-1·d^-1 intravenously, and children in control group were given erythromycin at 20~30 mg·kg^-1·d^-1, 7 d for 1 course of treatment. The 2nd day, the curative effect, peripheral serum IgA, IgG, IgM levels and the changes of T lymphocyte subsets were compared in the two groups. Results: The total effective rate was 94.55% in observation group, which was higher than 81.82% in control group (P<0.05). After treatment, peripheral serum IgA, IgG and IgM levels in the two groups were significantly lower than before treatment (P<0.01), peripheral serum IgA, IgG and IgM levels in observation group were significantly lower than in control group (P<0.01);Peripheral blood CD4⁺ content, natural killer cell content and the ratio of CD4⁺/CD8⁺ were significantly reduced, CD8⁺ content was increased significantly after treatment in the two groups (P<0.01). After treatment, in observation group, peripheral blood CD4⁺ content, natural killer cell content and the ratio of CD4⁺/CD8⁺ were significantly lower while CD8⁺ content was obviously higher than in control group (P<0.01). Conclusions: The curative effect of azithromycin on mycoplasma pneumoniae pneumonia is notable, which is better than that of erythromycin. Azithromycin and erythromycin both can adjust the immune function of organism effectively, but the role of azithromycin regulate the body's immune function is more obvious.