Von Willebrand disease (VWD) is a heterogeneous bleeding disorder caused by decrease or dysfunction of von Willebrand factor (VWF). A wide range of mutations in the VWF gene have been characterised; however their cellular consequences are still poorly understood. Here we have used a recently developed approach to study the molecular and cellular basis of VWD. We isolated blood outgrowth endothelial cells (BOEC) from peripheral blood of four type 1 VWD, four type 2 VWD patients and nine healthy controls. We confirmed the endothelial lineage of BOEC, then measured VWF mRNA and protein levels, both before and after stimulation, and VWF multimers. Decreased mRNA levels were predictive of plasma VWF levels in type 1 VWD, confirming a defect in VWF synthesis. However BOEC from this group of patients also showed defects in processing, storage and/or secretion of VWF. Levels of VWF mRNA and protein were normal in BOEC from three type 2 VWD patients, supporting the dysfunctional VWF model. However, one type 2M patient showed decreased VWF synthesis and storage, indicating a complex cellular defect. These results demonstrate for the first time that isolation of endothelial cells from VWD patients provides novel insight into the cellular mechanisms of the disease.