PURPOSE: Rome criteria are considered the gold standard for diagnosing functional constipation. The modified Bristol stool form scale (m-BSFS) was validated to measure stool form in children. However, neither the potential use of the m-BSFS as a tool to facilitate the diagnosis of potential constipation, nor the agreement between m-BSFS and stool consistency by Rome has been studied. Our objective is to determine if m-BSFS is a reliable tool to facilitat detection of constipation; and the agreement between stool form by m-BSFS and hard stool criteria in Rome. METHODS: A survey tool with the Rome III criteria and the m-BSFS was developed. A Likert-scale addressed frequency of each stool form on the m-BSFS. Responses to Rome III and m-BSFS were compared. RESULTS: The sensitivity and specificity of the m-BSFS was 79.2% and 66.0% respectively; and in children <4 years. improved to 81.2% and 75.0% respectively. There was poor agreement between hard stools by m-BSFS and the painful or hard bowel movement question of Rome Criteria. CONCLUSION: The potential utility of m-BSFS as a reasonably good tool to facilitate the diagnosis of potential constipation in children is shown. The poor agreement between painful or hard stool question in Rome III, and ratings for hard stool on the m-BSFS illustrates that one's perception may differ between a question and a picture. A useful pictorial tool to appraise stool form may, thus, be a favorable complement in the process of enquiry about bowel habits in well-child care.