Chronic constipation is a common condition in childhood, and despite current diagnostic methods its etiology remains unknown in 70% to 80% of the cases. Apropriate medical treatment is frequently effective but it has to be sustained and carefully done in order to restore intestinal function. Data from 40 children (21 girls) with chronic idiopathic constipation who were seen along a 10 years period at a pediatric gastroenterology clinic from a university associated hospital at Santiago, Chile, is shown. Symptoms begun before one year of age in 62% and before age 3 years in 82% of these patients. Sixty percent of them needed frequent use of laxatives, one third looked for medical care because of fecal runoff and 22.5% had psychological symptoms. A cross sectional study after one year follow up in 36 remaining patients showed that 21 (61-7%) of them were free of symptoms and apparently cured. After ten years it was possible to regain information from 16 patients, 14 of them were considered to be healthy and their x-ray studies were normal. The two remaining cases showed clinical, radiological and manometric evidence of an organic disease (myogenic achalasia, megarectus and megacolon) and both required surgical treatment. Possible causes of protracted course in children with chronic idiopathic constipation include genetic predisposition, failure to comply with treatment and chronic local inflamation and fibrosis due to persistent fecal mass.(Key words: Constipation, chronic, idiopatic, treatment, prognosis.)La constipation cronica es un problema fre-constituye una situation muy molesta para el cuente en la infantia. En los casos graves, cuando nino y la familia. En 70 a 80% de los pacientes, se acompana de fecaloma y escurrimiento fecal, los metodos radiologicos, manometricos e histologicos de estudio disponibles actualmente, no permiten demostrar alteraciones organicas y 1. Unidad de Gastroenterologia, Departamento de Petampoco existen alteraciones de los habitOS de diatria, Hospital Roberto del Rio.defecation o de alimentation que expliquen el