Functional gastrointestinal disorders are among the most common chronic disorders in children worldwide. Studies in schoolchildren from various Latin American countries have shown a high prevalence of functional gastrointestinal disorders, but their prevalence in Mexican schoolchildren is unknown. Our aim was to assess the prevalence of functional gastrointestinal disorders in Mexican schoolchildren in accordance with the Rome III criteria.Children and adolescents from public and private schools in Monterrey and Cuernavaca privately completed the Spanish version of the Questionnaire on Pediatric Gastrointestinal Symptoms-Rome III Version (QPGS-III) in class, using the same methods and questionnaires of previous studies conducted by our group in other Latin American countries.A total of 362 schoolchildren (public school 82, private school 280), with a mean age of 11.6±2.1 years completed the QPGS-III. Ninety-nine schoolchildren (27.3%) met the criteria for a FGID, according to the Rome III criteria. Functional constipation was the most common FGID (12.6%). Irritable bowel syndrome (6.4%) was the most common FGID associated with abdominal pain. There was no significant difference in the prevalence of FGIDs between sexes (P=.8).We found a high prevalence of FGIDs in Mexican school-aged children and adolescents.