Acute GIB is a serious and often life-threatening condition. It is typically categorized as either upper or lower depending on the anatomic location of the bleeding site. Upper gastrointestinal bleeding (UGIB) may involve the esophagus, stomach, and duodenum. It carries a mortality rate of approximately 10%. Its common causes in order of frequency are: Erosions or ulcers, variceal bleeding, Mallory-Weiss tear, vascular lesions, and neoplasms. Lower gastrointestinal bleeding (LGIB) may involve the small bowel, colon, and rectum. It is less common than UGIB and accounts for approximately 30% of all GIB. It carries a mortality rate of 3.6%. Its common causes in order of frequency are: Diverticular disease, angiodysplasia, neoplasms, colitis, and benign anorectal lesions. Available diagnostic procedures are either of low diagnostic accuracy such as barium examinations and scintigraphy, invasive such as catheter angiography or insensitive in localizing small bowel lesions such as endoscopy and capsule endoscopy. The introduction of multi-detector CT has markedly reduced acquisition times, and this minimizes image degradation from movement artifact caused by peristalsis or respiration, thus all vascular territories can be imaged simultaneously during the contrast bolus.