The most common cause of children chronic constipation is functional disorders. Functional constipation is diagnosed after excluding organic causes of constipation (anatomical, neurological, endocrinological) and identification of two symptoms defined by the Rome III criteria. There could be low number of bowel movements (below three times a week), defecation pain, fecal incontinence (once a week), stool consistency or occurrence of large diameter stools. The treatment is change of diet, defecation training and application of laxatives.