Children aged between 4 and 12 years were included in the study and the initial diagnosis of functional chronic constipation was made in accordance with the Rome III criteria. The children having attended the Pediatric Gastroenterology Ambulatory of the Federal University of Sao Paulo and the Santa Casa de Misericórdia hospital in Sao Paulo city. All of the children were undergoing constipation maintenance treatment with the use of a laxative in a dosage less than 1.0 ml/Kg for milk of magnesia, mineral oil or lactulose or less than 0.5 g/Kg for polyethylene glycol 3350.