To determine the effectiveness and safety of splenectomy for patients with human immunodeficiency virus (HIV)-related immune thrombocytopenia, using the results of splenectomy for patients with non-HIV immune thrombocytopenic purpura as a control group for comparison. Design: Retrospective study. Setting: Tertiary care university hospital. Patients: Fourteen patients who underwent splenectomy for symptomatic, medically refractory HIVrelated immune thrombocytopenia at this hospital from 1988 to 1997. During the same period, 20 patients had splenectomy for treatment of non-HIV immune thrombocytopenic purpura. Intervention: Splenectomy. Main Outcome Measures: Platelet response, need for postsplenectomy medical therapy, progression of HIV disease, and complications. Results: All patients with HIV-related thrombocytopenia had a complete early platelet response to splenec