Acquired von Willebrand syndrome (avWS) has gained more attention during the last years. An International Registry has been compared with the literature. It could be shown that the data collected from 123 publications compared well with the data from the registry, albeit with differences in the number of patients suffering from lymphoproliferative diseases and cardiovascular disorders, that were more prominent in the registry and the group of miscellaneous conditions underrepresented in the registry. Our data are clearly different for the lymphoproliferative diseases with only four patients in 2 years. These patients usually suffer from severe bleeding complications together with low to very low factor VIII/von Willebrand factor (FVIII/vWF) concentrations and thus will not go undiagnosed. In contrast to this, patients with cardiovascular disorders usually bleed only during surgical procedures or catheter procedures. At that time they have increased vWF parameters. Because of this and because the acute bleeding is of limited duration and usually not life threatening, many of them are discharged without a proper diagnosis and are only rarely referred to a specialized diagnostic work-up thereafter. In conclusion, avWS, although not a frequent disease, is nevertheless clearly underdiagnosed. This should be addressed in future prospective studies.