Vasculitides constitute a heterogeneous group of diseases characterized by inflammation of blood vessels. The skin is mainly affected, although the gastrointestinal tract mucosa can also be involved. The contribution of endoscopy in these cases has not been clearly determined. We report three cases of systemic vasculitis (polyarteritis nodosa, Schonlein-Henoch purpura and Behcet's disease) presenting with acute digestive bleeding. Endoscopy was an effective technique for completing the diagnosis and in establishing an effective nonsurgical therapeutic approach in these potentially lethal cases of gastrointestinal hemorrhage.