Acute upper gastrointestinal (UGI) tract bleeding is best initially investigated and treated with endoscopy. For patients who fail therapeutic endoscopy, both surgery and transcatheter arteriography and intervention (TAI) are equally effective. Transcatheter arteriography and intervention should be considered as a treatment option in patients with UGI bleeding, particularly those at high risk for surgery. Transcatheter arteriography and intervention for UGI bleeding has a low rate of major complications, and prolonged clinical success is seen in at least 65% of patients. Transcatheter arteriography and intervention is the best method of treatment for bleeding occurring into the biliary tree or pancreatic duct. In patients with acute lower gastrointestinal (LGI) tract bleeding who are hemodynamically stable, either colonoscopy or nuclear medicine scans can be used for diagnosis. Colonoscopy will identify the site of bleeding more frequently than other methods and can provide effective treatment. The use of emergent TAI is most appropriate for patients with massive LGI bleeding, because contrast extravasation is more likely to be seen on diagnostic arteriography, and this can then guide therapeutic embolization. Transcatheter arteriography and intervention may successfully stop bleeding in 40% to 85% of patients. Major complications from TAI are uncommon, but the risk for rebleeding is quite high, particularly when LGI bleeding originates from the jejunum, ileum, or cecum. Transcatheter arteriography and intervention is most effective for the treatment of bleeding from colonic diverticulitis and for bleeding occurring distal to the cecum. The choice of colonoscopy, TAI, or surgery for hemodynamically unstable patients with acute LGI bleeding will depend on institutional expertise and whether the site of bleeding has been localized.