In children, radiography is performed to diagnose vertebral fractures and dual energy x-ray absorptiometry (DXA) to assess bone density. In adults, DXA assesses both. We aimed to establish whether DXA can replace spine radiographs in assessment of paediatric vertebral fractures. Prospectively, lateral spine radiographs and lateral spine DXA of 250 children performed on the same day were independently scored by three radiologists using the simplified algorithm-based qualitative technique and blinded to results of the other modality. Consensus radiograph read and second read of 100 random images were performed. Diagnostic accuracy, inter/intraobserver and intermodality agreements, patient/carer experience and radiation dose were assessed. Average sensitivity and specificity (95 % confidence interval) in diagnosing one or more vertebral fractures requiring treatment was 70 % (58-82 %) and 97 % (94-100 %) respectively for DXA and 74 % (55-93 %) and 96 % (95-98 %) for radiographs. Fleiss' kappa for interobserver and average kappa for intraobserver reliability were 0.371 and 0.631 respectively for DXA and 0.418 and 0.621 for radiographs. Average effective dose was 41.9 mu Sv for DXA and 232.7 mu Sv for radiographs. Image quality was similar. Given comparable image quality and non-inferior diagnostic accuracy, lateral spine DXA should replace conventional radiographs for assessment of vertebral fractures in children. aEuro cent Vertebral fracture diagnostic accuracy of lateral spine DXA is non-inferior to radiographs. aEuro cent The rate of unreadable vertebrae for DXA is lower than for radiographs. aEuro cent Effective dose of DXA is significantly lower than radiographs. aEuro cent Children prefer DXA to radiographs. aEuro cent Given the above, DXA should replace radiographs for paediatric vertebral fracture assessment.