Retroanastomotic internal hernia is a rare but potentially lethal complication that occur after gastrojejunostomy. Whenever a gastrojejunostomy is made, whether removing a portion of stomach of not, one or two internal rings are formed anatomically according to the antecolic or retrocolic anastomosis and part or all of the small bowel can be through these rings. The symptom of retroanastomotic hernia are not typical to make a correct diagnosis before operation but one should at least suspect the possibility of this complication in patient who has had a gastroenteric anastomosis. Compare with other literatures, the occurrence according to antecolic or retrocolic anastomosis was similar but the mortality in Korea was 17%(though the mortality of our hospital were 50%) and it is comparable with other reports. In order to stress the importance of the retroanastomotic hernia and to prevent this serious complication, we reported 6 cases of the retroanastomotic hernia we have been experienced recently, with reviewed the literature.