This prospective study assessed von Willebrand factor (VWF) expression in the endometrium using immunohistochemical staining in women with menorrhagia with or without von Willebrand disease (VWD) compared with a control group of women with normal menstrual loss. Endometrial VWF expression is significantly lower in women with VWD, which may play a local underlying role in pathogenesis of menorrhagia in these women.