This is an open-label, non-randomized, phase II study to assess the efficacy and safety of eltrombopag in Japanese moderate or more severe aplastic anemia (AA) subjects with a platelet count <30,000/ microliter who are refractory to anti-thymocyte globulin (ATG)-based immunosuppressive therapy (IST), who have relapsed after ATG-based IST, or who are ineligible for ATG-based IST.