Objective: Learn some immunological traits in the peripheral blood of patients with thrombocytopenia of unknown cause after splenectomy treatment. Subjects and Methods: Research methodology: a retrospective, cross-sectional descriptive. Study subjects included 27 patients with thrombocytopenia of unknown cause in the period after splenectomy from 6 months to 5 years (average 38.59 months). Results: After splenectomy phenomenon humoral immune prolonged (P 0.005). In which mainly reduced levels of IgG, IgM. In response group and not fully meet the levels of IgG, IgM, IgA higher complete response group. Increase the number of lymphocytes TCD3, TCD4, CD8 T cells and reduced the number of CD19, but not different from normal, TCD4/TCD8 ratio 1. Conclusion: After splenectomy phenomenon humoral immune lasts. In which mainly reduced levels of IgG, IgM. In the group does not respond and do not respond fully IgG levels, IgM, IgA higher complete response group. Increase the number of lymphocytes TCD3, TCD4, CD8 T cells and reduced the number of CD1, but not different from normal however TCD4/TCD8 ratio 1.