Methods: The investigators performed a randomised, double-blind, placebo-controlled, single centre study to assess the long-term efficacy and safety of thalidomide 100mg qn p.o. or placebo 100 mg qn p.o. administration for 4 months in subjects with recurrent gastrointestinal bleeding due to vascular malformations. Patients with at least six episodes of bleeding in the prior year due to vascular malformation were randomly grouped, prescribed a four-month regimen of either 100mg of thalidomide or 100 mg of placebo orally one time daily, and monitored for at least one year. The primary end point was defined as the patients whose rebleeds decreased from baseline by ≥ 50% at 12 months. Rebleeding was defined based on a positive fecal occult blood test (FOBT) (monoclonal colloidal gold color technology) at any visit after treatment. Secondary outcomes included the changes from baseline in participants dependent on blood transfusions and transfused packed red cell units, bleeding episodes, bleeding durations, and hemoglobin levels at 12 months. Statistical significance was defined at P < 0.05.