The author reviewed the clinical features of children with Hirschsprung's disease (HD) and its allied disorders [hypoganglionosis (Hypo) and intestinal neuronal dysplasia (IND)] before and after anorectal myectomy (ARM). The incidence was greater in males than in females (1.5:1). The patients were between 0 and 15 years of age and more than half were less than 6 years old. Neurohistochemical examination showed Hypo [mild type (3/5 or more ganglion cells per ganglia compared with normal ganglia), severe type (less than 2/5 ganglion cells per ganglia compared with normal ganglia), IND, and HD (aganglionosis). Mild Hypo was the most common, compared with HD and NID. Abdominal pain was the most common symptom, followed by soiling and anal pain. Spontaneous evacuation without the need for laxatives was noted in 70~75% patients with a good outcome, and 30~40% of those with a satisfactory outcome after ARM. Patients with a poor outcome still required laxatives and other medical treatment. Related causes of constipation, i.e., colonic inertia, psychological or central nervous disorders, occurred at a higher incidence in those with a poor outcome. The most common related cause of constipation after ARM was colonic inertia, i.e., redundant colon. Additional operations (subtotal colectomy and ileorectal anastomosis) were performed for the patients with a poor outcome. These patients were satisfied with the postoperative state of evacuation. In conclusion, the abnormal distribution of ganglia, i.e. Hypo, IND, and HD could be largely related to the defecation disorders observed in childhood patients with chronic constipation. Patients with severe Hypo, IND, and HD, especially those with long affected colon, psychological or central nervous disorders, may experience significant persistent constipation after ARM. Additional operations should be performed in patients with a poor outcome due to colonic inertia.