OBJECTIVE: Internal hernias, including paraduodenal (traditionally the most common), pericecal, foramen of Winslow, and intersigmoid hernias, account for approximately 0.5-5.8% of all cases of intestinal obstruction and are associated with a high mortality rate, exceeding 50% in some series. To complicate matters, the incidence of internal hernias is increasing because of a number of relatively new surgical procedures now being performed, including liver transplantation and gastric bypass surgery. A significant increase in hernias is occurring in patients undergoing transmesenteric, transmesocolic, and retroanastomotic surgical procedures. It is important for radiologists to be familiar with and to understand the various types of internal hernias and their imaging features so that prompt and accurate diagnosis of these conditions can be made. CONCLUSION: This article illustrates the imaging findings of internal hernias, with emphasis placed on the CT findings, especially in transmesenteric, transmesocolic, and retroanastomotic types of internal hernias.