 Eligible patients can have treated or untreated MAA, as well as counts meeting criteria for MAA following a partial response to treatment with immunosupression for SAA. We will also include patients with bone marrow failure and unilineage cytopenia. Treatment response for the platelet lineage is defined as platelet count increases to 20,000microL above baseline at 16 to 20 weeks, or freedom from platelet transfusions for greater than or equal to 8 weeks in transfusion-dependent patients. For patients with anemia untransfused hemoglobin less than or equal to 8.5 gdL, a treatment response will be an increase in Hb by greater than or equal to 1.5gdl at four months, measured on at least 2 serial measurements and sustained for 1 month or more without transfusion support OR for transfusion dependent patients, reduction of units of RCC transfused by 50 percent8 weeks compared with the pretreatment transfusion number in the previous 8 weeks or transfusion independence no transfusions for greater than or equal to 8 weeks. Subjects with evidence for a clinical response in any lineage at 16 weeks but not yet meeting full primary endpoint response criteria, and who are tolerating investigational treatment, may receive an additional 4 weeks of eltrombopag and be reassessed after 20 weeks. At that time, if they meet primary endpoint response criteria, they will be eligible to enter the extended access part of the study. If they do not meet primary endpoint response criteria, eltrombopag will be discontinued. 