Pharmacologic treatment of bleeding gastrointestinal arteriovenous malformations is difficult. These lesions should be treated pharmacologically only when endoscopic treatment is not successful and bleeding persists or when the lesions cannot be treated endoscopically due to their localization, mainly in the small bowel. These are only a limited number of studies available on the medical treatment of bleeding arteriovenous malformations. There is considerable evidence, however, that a combination of estrogens and progestagens significantly reduces the bleeding frequency and intensity and also the transfusion requirements in patients with high transfusion need. A few other drugs have been tried in patients with bleeding gastrointestinal arteriovenous malformations: danazol, octreotide, desmopressin, and aminocaproic acid. The experience with these drugs, however, is limited to case reports or to small series of patients.