Aim The Rome IV criteria for the diagnosis of functional constipation are one month, compared with two months in the Rome III criteria. Our aim was to see whether this altered the prevalence in Ecuador by surveying school children and comparing the results to our previous study. Methods A cross‐sectional study was conducted in Quito, Ecuador, in 2013 two randomly selected schools: one private and one public. Children aged 8–15 completed the Spanish version of the Questionnaire of Paediatric Gastrointestinal Symptoms based on the Rome IV criteria. We compared our findings with our previous 2013 study based on the Rome III criteria. Results A total of 951 children (61% male) completed the Rome IV questionnaire from June to July 2017 at a mean age of 11.2 ± 1.8 years, and 417 children (52% male) completed the Rome III questionnaire in June 2013 at a mean age of 12.0 ± 1.8 years. We found that 14.4% met the Rome IV criteria for functional constipation compared with 11.8% for the Rome III criteria (p = 0.11). Conclusion Modifying the time required for a diagnosis functional constipation from two months to one month did not result in a significant difference in the prevalence.