Eltrombopag olamine (SB-497115-GR) is an orally bioavailable, small molecule thrombopoietin receptor agonist that may be beneficial in medical disorders associated with thrombocytopenia. Eltrombopag has been shown to increase platelet counts in patients with thrombocytopenia from various etiologies (Idiopathic thrombocytopenic purpura [ITP], liver disease, aplastic anemia and chemotherapy induced thrombocytopenia). Approximately 350 subjects will be randomized in a 1:1 ratio (175 into the eltrombopag arm and 175 into the placebo arm). Approximately 55 subjects will be enrolled into the azacitidine. Subjects with intermediate-1, intermediate-2 or high risk MDS by IPSS, and baseline platelet count of <75 Giga (10^9) per liter (Gi/L) will only be enrolled. This is a randomized, double-blind, parallel group, placebo-controlled study designed to explore the platelet supportive care effects of eltrombopag versus placebo in combination with the standard of care hypomethylating agent, azacitidine. The primary objective of this study is to determine the effect of eltrombopag versus placebo on the proportion of subjects who are platelet transfusion free during the first 4 cycles of azacitidine therapy. Key secondary endpoints include overall survival, disease response, and disease progression.