The term ultrashort Hirschsprung's disease has been used to define a spectrum of conditions with clinical presentation similar to Hirschsprung's disease but with presence of ganglion cells on rectal biopsy. In contrast to Hirschsprung's disease, there is no transition zone on barium enema. However, as in classical Hirschsprung's disease, there is no reflex internal sphincter relaxation on rectal manometry. We reviewed the presentation of five patients with chronic constipation who fulfilled the criteria for ultrashort Hirschsprung's disease. After positive anorectal manometry, despite the presence of ganglion cells on suction rectal biopsy, internal sphincter myomectomy was performed in four patients. Resolution of symptoms was noted in all operated patients. Normal ganglion cells were present throughout the entire length of all myomectomy specimens. There is controversy in the literature concerning the diagnosis of ultrashort Hirschsprung's disease. Most of the confusion concerns whether a short segment of aganglionosis proximal to the dentate line is permissible for the diagnosis of ultrashort Hirschsprung's disease and to what extent such aganglionosis is physiological. Perhaps it would be more accurate to define this entity by the presence of ganglion cells on rectal biopsy as well as the failure of the internal sphincter to relax on rectal manometry and to describe it as anorectal achalasia in severely constipated patients.