Recent research demonstrates that the underlying mechanism in immune thrombocytopenia (ITP) is very complex. Lymphocyte function associated antigen-1 (LFA-1) plays important roles in autoimmune diseases. The purpose of this study was to investigate the expression of CD11a on lymphocytes and explore its possible role in ITP. The expression of CD11a on lymphocyte subpopulations (CD3(+) T cells, CD3(+)CD4(+) T cells, CD3(+)CD4(-) T cells, CD4(+)Foxp3(+) T regulatory cells and CD19(+) B cells) were analyzed by flow cytometry. Specific anti-platelet GPIIb/IIIa and/or GPIb/IX autoantibodies were assayed by modified monoclonal antibody specific immobilization of platelet antigens (MAIPA). The mean fluorescence intensity of CD11a on CD3(+) T, CD3(+)CD4(-) T and CD19(+) B lymphocytes were increased in ITP patients compared to healthy controls. No significant difference of CD11a expression on CD3(+)CD4(+) T cells or CD4(+)Foxp3(+) T regulatory cells was found between ITP patients and controls. Our data indicates the possible role of CD11a in the pathogenesis of ITP.