The aim of this study was to present and discuss the anatomical basis of internal hernias thanks to our clinical experience of 14 cases. Internal hernias are uncommon cases of acute intestinal obstruction when a viscera protrudes through an intraperitoneal orifice, remaining inside the peritoneal cavity. It excludes iatrogenic post surgical hernias. From an anatomical point of view, three kinds of orifices may be interested. The orifice may be normal: epiploic or omental (Winslow's) foramen, or abnormal through a pathologic transomental hole realizing an internal prolapsus or procidentia, without sac. Or this orifice may be a paranormal peritoneal fossa (para duodenal or retrocaecal) acting as a trap for the bowel: these hernias possess a sac and are considered as true hernias. The clinical diagnosis is always difficult. CT scan can be useful confirming the obstruction and leads to an urgent operation. This retrospective study evaluates diagnosis, management and follow-up according to the type of anatomical orifice and delay of surgery.