The treatment of a boy is reported, who suffered from a combination of vesico-intestinal fissure and meningocystocele. Because five of seven patients known to us since 1969 had a similar combination, it should be analysed whether there exists an etiological or embryological connection. Therefore the pertinent literature and clinical data of known patients was collected and evaluated. It can be shown that also in the literature a coincidence of 75% of vesico-intestinal fissure and meningomyelocele is reported and both are caused during the 4th week of embryological development. Vesico-intestinal fissure is a disturbance of mesodermal inflow into the lower abdominal wall. The cause for meningocystocele is an abnormal cell proliferation of the neural anlage. Despite a number of possible clues an etiological connection could not be proved.