Gastrointestinal bleeding is a common and potentially life-threatening problem. The incidence of upper gastrointestinal bleeding (UGIB) is 40 to 150 episodes per 100,000 population per year. Mortality in large series is 6% to 10% for UGIB and has remained unchanged over the past 30 to 60 years. The incidence of hospitalization for acute lower gastrointestinal bleeding is about 20 to 27 episodes per 100,000 population per year, with a 200-fold increase with advancing age from the third to ninth decades. The mortality rate is 4% to 10% or higher. The evaluation of overt or acute gastrointestinal bleeding in the ED is reviewed here from the perspective of evidence-based medicine.