Abstract: Objective To study the clinical features and immune-mediated pathogenesis of mycoplasma pneumonia (MP) in children. Methods The DNA of mycoplasma in nasopharyngeal swabs was detected by PCR in 485 children with respiratory tract infection, and serum circulating immune complex (CIC), IgG, IgM, MP IgM, and CH50 were measured on the same day in 45 children with pneumonia. Results Significant difference was noted between the results of mycoplasma DNA PCR detection and those of serum IgM detection. The positivity rate of CIC was 44% in children with MP whereas that in the control group was only 10% (P<0.01). The levels of serum IgG and IgM in MP group was significantly higher and serum CH50 lower than those of the control group (P<0.05). Conclusion Mycoplasma DNA detection facilitates early diagnosis and treatment of MP, whose pathogenesis in children may be involved in immune-mediated mechanism.