Autopsy records of 9 cases of neonate Hirschsprung's enterocolitis (HD) and 16 cases of neonate necrotizing enterocolitis (NEC) were analysed. It was found that the NEC lesions were more extensive than HD lesions, the bleeding and inflammation in NEC were also more serious than in HD. From our 21 animal experiments in which we tried to clarify the pathogenesis of Hirschsprung's enterocolitis and NEC, our preliminary hypothesis fro the development of Hirschsprung's enterocolitis being: the distal segment was first obstructed, causing the proximal segment to expand, the increase of pressure within the bowel resulted in ischemia of the intestines, increased bacterial multiplication in the retained feces and bacterial infiltration of the intestinal mucosa. The above being the major cause of HD. When the neonate is in asphyxia or shock, ischemia of the intestines and immunoallergic reactions occur, due to the lack of IgA in the mucosa, the multiplication and infiltration of pathogenic enterobacteria in the intestinal wall results in NEC.