Objective: The aim of this study was to create a reference about normal pubic symphysis and sacroiliacjoint widths of children and adolescents.Methods: A total of 1020 computerized tomography axial scans of patients without pelvic injury between2 and 18 year-old were studied. The narrowest width of pubic symphysis and bilateral sacroiliac jointswere measured.Results: The average pubic symphyseal width at 2 years old boys was 6.35± 1.06 mm (4.88e9.13 mm).The average of right and left sacroiliac joints' widths at 2 years old boys was 4.56± 0.65 mm (3.59e6.07 mm) and 4.58 ± 0.66 mm (3.44e5.74 mm), respectively. The average pubic symphyseal width of 2years old girls was 5.85± 1.14 mm (4.06e8.20 mm). The average of right and left sacroiliac joints' widthsat 2 years old girls was found 4.36± 0.56 mm (3.50e5.37 mm) and 4.42 ± 0.59 mm (3.58e5.73 mm),respectively. The average pubic symphyseal width at 18 years old boys was found 3.68± 1.30 mm (1.90e5.79 mm). The average of right and left sacroiliac joints' widths at 18 years old boys was found1.97± 0.21 mm (1.73e2.41 mm) and 2.04 ± 0.30 mm (1.70e2.65 mm), respectively. The average pubicsymphyseal width at 18 years old girls was 3.92± 0.52 mm (2.97e4.76 mm). The average of right and leftsacroiliac joints' widths at 18 years old girls was found 2.34± 0.40 mm (1.58e3.34 mm) and2.33± 0.37 mm (1.58e3.10 mm), respectively.Conclusion: Our results suggest that one should be suspicious about pelvic injury if the width of pubicsymphysis is over 10 mm and width of sacroiliac joint is over 8 mm especially in patients younger than10 years-old.Level of Evidence: Level III Diagnostic study.© 2017 Turkish Association of Orthopaedics and Traumatology. Publishing services by Elsevier B.V. This isan open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).