The Bristol Stool Form Scale (BSFS) and a modified child-friendly version (M-BSFS) are frequently used in clinical practice and research. These scales have not been validated in children. 3-D stool scale models may be better adapted to the child's development.To assess the usefulness of the BSFS, M-BSFS, and a newly developed 3-D stool scale in children.Fifty children were asked to rank the picture cards of the BSFS and 3-D models from hardest to softest and to match the pictures with descriptors for each stool type.Thirty percent of the children appropriately characterized the stools as hard, loose, or normal using the BSFS vs. 36.6% with the 3-D model (p=0.27). Appropriate correlation of stools as hard, loose, or normal consistency using the BSFS vs. the 3-D model by age group was: 6 to 11-year-olds, 27.5% vs. 33.3% (p=0.58) and 12 to 17-year-olds, 32.1% vs. 39.5% (p=0.41). Thirty-three percent correlated the BSFS pictures with the correct BSFS words, 46% appropriately correlated with the M-BSFS words, and 46% correlated the 3-D stool models with the correct wording.The BSFS and M-BSFS that are widely used as stool assessment instruments are not user-friendly for children. The 3-D model was not found to be better than the BSFS and the M-BSFS.