On November 20, 2008, eltrombopag (Promacta) received approval from the US Food and Drug Administration (FDA) for the treatment of thrombocytopenia in patients with chronic immune thrombocytopenic purpura (ITP) who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. This report summarizes the FDA analyses of the clinical data supporting this approval.