Acquired von Willebrand disease (AvWD) is an acquired bleeding disorder which may suddenly become manifest in individuals, usually in the absence of a personal or family history of bleedings and frequently in association with monoclonal gammopathies, lymphoproliferative, myeloproliferative and autoimmune disorders. In a minority of the cases AvWD may develop in association with drugs or solid tumours. Pathogenetic mechanisms involve autoantibodies directed against von Willebrand factor (vWF) resulting in a rapid clearance of vWF from the circulation and/or inactivation of plasma vWF; absorption or adsorption of plasma vWF to malignant cells; drug-induced or cell-mediated proteolysis of plasma vWF; acquired decrease in synthesis of vWF and/or release of vWF from storage sites; or precipitation of plasma vWF. Treatment options include--whenever possible--treatment of the underlying disorder or symptomatic treatment aimed at replacing the loss of vWF by either infusion of vWF-rich concentrates or administration of desmopressin (DDAVP). In selected cases with anti-vWF antibodies, administration of high-dose intravenous gammaglobulin, plasma exchange or extracorporeal immunoadsorption may be successful.