In order to better understand the natural history of chronic functional constipation, a questionary was applied to 163 children and infants, before beginning standardized treatment. Median age (range) at start was 3mo(0-108mo) but age at arrival at the Pediatric Gastroenterology Unit was 53mo(2-146mo). In 62,4% of the cases symptoms began before or up to 3mo after cow's milk introduction and rarely around (±6mo) toilet training. Possible complications appeared progressively, often at preschool or school age or as the first noticeable manifestation: recurrent abdominal pain (61,1%), fecal soiling (45,4%), fecal blood (35%), enuresis (23,3%), vomiting (19%), urinary infection (17,9%), urinary retention (8,6%). Abdominal distension was rarely detected on physical examination and was usually discrete. In conclusion, children attended in Botucatu begin their constipation at an early age, frequently associated with weaning, and important complications may ensue along years. This evolution should be avoided by prevention and early treatment of constipation.