Constipation is very common in all age groups and can be resistant to standard therapies, producing chronic morbidity. Childhood onset constipation frequently produces symptoms that persist into adulthood. Recent advances have been made in the diagnosis and treatment of childhood constipation that could have application in adult practice. In the first part of the present review, the methods of differentiation of patients with a disorder of colonic motility from those with an anorectal hold-up are discussed. Slow transit constipation, with distinct features on colonic manometry and scintigraphy, has only recently been recognized in children. This diagnosis, together with a novel method of placement of a manometric catheter, is described. While the cause of slow transit constipation remains unclear, clinical features that differ between children and adults may provide an insight into the aetiology. The diagnosis of intestinal neuronal dysplasia is explained and the controversy surrounding the diagnosis outlined. We propose that the traditional histological criteria exclude many other clinically significant forms of dysplasia of the enteric nervous system and should be extended.