It is well-known that some patients exhibiting the symptoms of Hirschsprung's disease are shown to have intramural ganglia in the distal myenteric plexus. Some of them have been described as “pseudo-Hirschsprung's disease.”1–3 It is likely that a variety of conditions have been included in this group. Using a silver impregnation technique we have made a detailed histologic study of the rectum and large bowel in a number of cases with provisional clinical diagnosis of Hirschsprung's disease but in which rectal biopsy showed small ganglia in Meissner's plexus demonstrated by acetylcholinesterase (Ach-E) staining. Three histologic variations were shown that may be called hypoganglionosis, immaturity of ganglia, and hypogenesis. An attempt is made to relate their clinical picture to the histologic findings.