Abstract: Objective: To explore the changes of T cell subsets in Mycoplasma pneumonia(MPP) children with different chest X-ray manifestations.Methods: One hundred and fifty-six children with MPP were divided into group A and group B according to the lobar pneumonia change.The chest X-ray in group A and group B showed the lobar pneumonia change and non-lobar pneumonia change,respectively.Sixty-two healthy children were set as the control group(group C).The T cell subsets in 3 groups were detected and analyzed.Results: Compared with group C,the levels of CD4⁺ and CD4⁺/CD8⁺ in group A were significantly lower,while the level of CD8⁺ in group A was significantly higher(P<0.01).Conclusions: Immune injury plays an important role in the pathogenesis of MPP.The chest X-ray in older MPP children shows lobar pneumonia,which is strongly immunodepressed.