Bleeding from gastrointestinal angiodysplasia in patients with aortic stenosis (AS), termed Heyde's syndrome, has been recognized for many years. Intestinal angiodysplasia (IA) and AS are chronic degenerative diseases that are often asymptomatic, with a higher prevalence in the population than is clinically apparent. The incidence of both conditions increases with age, and both are associated with traditional cardiovascular risk factors. Many studies suggest that there is an increased prevalence of IA in AS and vice versa, but there is wide variation between studies. Evidence is mounting that severe AS may cause Type 2 acquired von Willebrand's disease, also termed von Willebrand's syndrome. This involves loss of the large multimers, which are required to maintain hemostasis in high flow conditions, such as occur in angiodysplastic arteriovenous malformations. Heyde's syndrome appears to consist of bleeding from previously latent intestinal angiodysplasia as a result of this acquired hematological defect, which is associated with aortic stenosis. Treatment options include localization of angiodysplastic bleeding points with cauterization, but this is associated with a high recurrence rate. Aortic valve replacement has been shown to improve the hematological abnormalities, and this is paralleled by clinical improvements. Valve replacement appears to offer the best hope of long-term resolution of the bleeding, and should be considered in most cases, particularly in those in whom the AS is symptomatic. In those patients deemed unfit for surgery in whom no bleeding point can be identified, recurrent blood transfusions may offer some symptomatic relief.