Conflict-of-interest disclosure: D.P. serves as a consultant for Amgen, GlaxoSmithKline (GSK), Shionogi, ONO, and Eisai; receives research support from Amgen, GSK, and Baxter Healthcare; and serves on the speakers bureau for Amgen. R.S. receives honoraria for participation on advisory boards and/or as a speaker at medical education events supported by GSK and Amgen. A.C.N. receives research funding from Amgen, Baxter, GSK, and Genentech; serves on speaking panels for Amgen and GSK and on advisory boards for GSK and PanGenetics; has no financial interest (stocks and shares); is not employed by any relevant company; and has no patents pending. V.S.B. serves on the Bayer International Haemophilia Advisory Board and is a member and chair of Novo Nordisk PRO-PACT Advisory Board. P.B.M. receives support from Baxter for travel to international meetings (International Society on Thrombosis and Haemostasis Scientific and Standardization Committee meeting, Vienna, Austria, 2008, and American Society of Hematology meeting, New Orleans, LA, 2009); participates in advisory board meetings for both Amgen and GSK; and served as chair of a satellite meeting for Baxter at the 2009 British Society for Haematology meeting. J.B.B. receives clinical research support from Amgen, Biogen-IDEC, Cangene, Genentech, GSK, Genzyme, Immunomedics, Ligand, MGI Pharma/Eisai Inc, and Sysmex; participates in speakers bureau programs for Baxter, Amgen, and GSK; owns stock in Amgen and GSK; participates in advisory boards for Amgen, GSK, Ligand, and Baxter; and participates in discussions of unlabeled or investigational use of product(s) that might include anti-cd40 ligand, thrombopoietic agents (AMG531 [Amgen], Eltrombopag [GSK], AKR501 [AkaRx]), Rigel, and rituximab [Genentech/Biogen-IDEC]. B.H.C. is a member of the scientific advisory boards of GSK, Amgen, Commonwealth Serum Laboratory (CSL), Bayer, and Boehringer Ingelheim; and serves as a consultant for CSL and Boehringer Ingelheim. D.B.C. serves as a consultant for Amgen, GSK, Symphogen, Genzyme, and Shionogi. T.B.G. receives research funding from and serves as a consultant for Amgen and GSK. B.G. serves as a consultant for Roche France, Amgen, and Laboratoire de fractionnement et de Biotechnologies (LFB; Les Ulis, France). J.G. receives honoraria for participation on advisory boards for GSK, Amgen, and Baxter, and receives research support from Baxter. B.J.H. lectures at meetings sponsored by Baxter. P.A.I. receives research funding from Amgen, GSK, and Roche, and serves as a consultant for Symphogen. R.M. owns stock in GSK and serves as ad hoc consultant for Amgen and GSK. F.R. receives honoraria for participation in advisory boards and/or as a speaker at medical education events supported by Amgen, GSK, and Shionogi. D.J.K. receives research support from and serves as a consultant for GSK, Amgen, MGI Pharma, Ligand, ONO, and Shionogi. I.G., G.L., M.A.S., M.T., S.W., and J.Y. declare no competing financial interests.