Abstract: Objective To investigate the effect of prednisone on apoptosis signal pathways of T lymphocyte and NK lymphocyte in peripheral,from the point that prednisone could alleviate the symptom of patients with Idiopathic thrombocytopenic purpura(ITP). Methods Thirty-one incipient ITP patients were treated by prednisone for 6 months.The flow cytometry was adapted to detect molecules(CD95L,Caspase-3,and Caspase-8) on T cells and NK cells lymphocyte before and after treatment. Results Compared with the levels before treatment,the expression of CD3,NK,CD3⁺CD95L⁺,and CD3⁺Caspase-8⁺ were significantly increased(P＜0.05) and NK⁺Caspase-8⁺was significantly decreased(P＜0.05).It was positive correlation both NK⁺Caspase-8⁺and NK⁺Caspase-3⁺(P＜0.01),and NK⁺Caspase-3⁺was positively correlated with NK⁺CD 95L⁺(P＜0.01),it showed that Caspase and Fas-FasL were associated with apoptosis pathway on NK cells.It was positive correlation both CD3⁺Caspase-8⁺and NK⁺Caspase-8⁺(P＜0.01),it showed that T lymphocyte start with NK cells apoptosis process. Conclusion Prednisone may regulate apoptosis signal pathway (CD95L,Caspase-3,and Caspase-8)mediated by T and NK lymphocyte to alleviate the symptom of patients,which can be used as a reference for clinical treatment.