For optimal care of patients with the moderate and severe form of von Willebrand disease a better understanding of symptoms, diagnostics, treatment and complications of treatment is necessary. The present study aims to register and investigate all patients in the Netherlands with moderate and severe von Willebrand disease to gain understanding of the clinical presentation, the treatment and the complications of treatment in moderate and severe von Willebrand disease. Another goal is to investigate the influence of von Willebrand disease on quality of life.