Two cases of von Willebrand's disease and angiodysplasia with intractable gastrointestinal bleeding are presented. Replacement therapy with cryoprecipitate and variable purity von Willebrand factor (VWF) was ineffective, as were other treatments including steroids, immunoglobulin and hormonal replacement. Both patients required massive blood transfusion and product support. The efficacy of somatostatin and an analogue is described. In one patient, we observed a rise in von Willebrand factor activity after octreotide infusion.