Objective To sudy the changes in mTOR signaling pathway in childhood aplastic anemia(AA) by detecting the expression levels of the molecules of mTOR signaling pathway in T cells, and to explore immunologoical pathogenesis of AA in children from T cell intracellular signal transduction pathway. Methods Peripheral blood samples were collected from 16 newly diagnosed severe AA(SAA) patients and 8 patiens treated with effective immunosuppressive therapy, and the findings were compared with those of 17 healthy children (normal controls) and CEM cells(positive controls). The expressions of p-Akt, p-TSC2, p-mTORC1, p-4EBP1, p-p70S6K in CD3+ T cells in peripheral blood were detected by flow cytometry(FCM). Results 1.The expressions of p-Akt, p-TSC2, p-mTORC1, p-4EBP1, p-p70S6K of the newly diagnosed SAA group were higher than those of the normal control group(P 0.05), but the expressions of p-4EBP1 were higher(P<0.05). The MFI was followed by 3.28±1.27, 16.50±10.91, 3.54±1.66, 74.89±49.69 and 4.21±1.69. Conclusions 1.The expressions of p-Akt, p-TSC2, p-mTORC1, p-4EBP1, p-p70S6K were increased in the newly diagnosed SAA patients, the mTOR signaling pathway was activated in SAA patients.2.The expressions of p-Akt, p-TSC2, p-mTORC1, p-4EBP1, p-p70S6K were lower than those of the newly diagnosed SAA patients.The degree of activation of mTOR signaling pathway was associated with disease status.The signaling pathways may be involved in the T cells of AA of the immune abnormalities. Key words: Aplastic anemia; T cell; Mammalian target of rapamycin; Signaling pathway