: Acquired coagulopathies are common; uncommonly, adsorption of coagulation factors from the circulation into the tissues by pathologic amyloid exceeds the body's ability to produce factor and results in acquired factor deficiency. When amyloidosis does cause a coagulopathy, it is most often acquired factor X deficiency, but there are rare reports of amyloidosis being associated with other acquired factor deficiencies. We investigated a case of a severe bleeding diathesis, the cause of which was combined acquired factor V deficiency and concomitant acquired von Willebrand syndrome. Studies revealed prolonged prothrombin time and activated partial thromboplastin time. Mixing patient plasma with normal plasma corrected both the prothrombin time and activated partial thromboplastin time. Assays showed decreased factor V activity of 27%; Ristocetin cofactor activity was decreased at 49%, but von Willebrand antigen was elevated at 213%. Multimer analysis was consistent with type 2 von Willebrand syndrome. Lymph node biopsy documented amyloid light chain type (AL) amyloidosis; extraction of protein from the lymph node documented AL lambda light chain amyloid. Marrow biopsy documented IgG lambda myeloma. Immunohistochemical staining of the lymph node, using investigational polyvalent antibodies, demonstrated that both von Willebrand factor and factor V were identifiable in areas of amyloid deposition, providing evidence that these coagulation factors were adsorbed to the amyloid protein, resulting in accelerated clearance from the circulation, previously reported to be the mechanism of cases of acquired factor X deficiency in the setting of amyloidosis. Although there are case reports of acquired von Willebrand syndrome because of amyloidosis and case reports of acquired factor V deficiency because of amyloidosis, this appears to be the first reported case of concomitant acquired von Willebrand syndrome and acquired factor V deficiency because of amyloidosis, and the first report of localization of both von Willebrand protein and factor V protein to AL amyloid as a cause of a severe bleeding diathesis.