Abstract: Objective: To explore the diagnostic value of C-reactive protein(CRP) in children with mycoplasma pneumonia(MP). Methods: The serum CRP levels were measured in 98 Mycoplasma pneumonia children(group A),69 bacteria pneumonia children (group B),89 virus pneumonia children(group C) and 50 healthy children(group D) by nephelometric immunoassay. Results: The ratio of positive of group A, B, C and D are respectively 31.63%,92.75%,6.74% and 2.00%; the levels of serum CRP are respectively (15.37 ±10.23),(42.81 ±15.62),(3.93 ±2.35) and (2.82 ±0.98) mg/L. The positive ratio and levels of serum CRP between each two groups were significantly different(P < 0.01). Conclusions: The results indicate that the serum CRP level could have important value for diagnosis in children with mycoplasms pneumonia.