Heyde's syndrome is characterized by gastrointestinal bleeding due to angiodysplasias of the gut associated with calcific aortic stenosis. This association does not seem to be a patho-etiological entity but an occasional coincidence in the elderly. Aortic valve replacement (preferably with a bioprothesis) has been postulated to be the treatment of choice for the cure of the bleeding. Two cases of this syndrome are reported on. In one of the cases implantation of a bioprosthesis was accompanied by almost immediate cessation of bleeding, but with reoccurrence after one year necessitating local therapy. In the other case postoperative bleeding following aortic and mitral valve replacement with mechanical prostheses and tricuspid annuloplasty was the reason for coloscopic examination, which showed areas of angiodysplasia in the ascending colon. However, apart from a pause in anticoagulation medication no additional therapy was required since the hemorrhage ceased.