Objective  To investigate the clinical significance of the appearance time of serum anti-mycoplasma pneumonia immunoglobulin M (MP-IgM) antibody in children with mycoplasmal pneumonia, and to analyze the clinical characteristics of children with positive MP-IgM at different time.

  Methods  The clinical materials of 200 children with mycoplasmal pneumonia were retrospectively analyzed.

  Results  Among 200 children with mycoplasmal pneumonia, 124 cases were detected as positive MP-IgM within 7 to 10 days, 69 cases were detected as positive MP-IgM within 11 to 14 days, and 7 cases were detected as positive MP-IgM within 15 days or longer (the positive time was later).

  Conclusion  For children with mycoplasmal pneumonia, the cases with late occurrence time of positive MP-IgM are more serious in manifestations and difficult in treatment, and they should be treated with strengthened therapy, and intervention for mycoplasma pneumoniae infection should not be stopped untimely because there is no mycoplasma antibody in the early stage.