von Willebrand disease (VWD) is an inherited bleeding disorder that is caused by deficiency or dysfunction of von Willebrand factor (VWF), a plasma protein that mediates the initial adhesion of platelets at sites of vascular injury and also binds and stabilizes blood clotting factor VIII (FVIII) in the circulation. This book examines the need for more information on VWD prevalence and the relationship between low VWF levels of bleeding symptoms or risk and improving clinical and laboratory diagnostic tools.