Objectives: Diagnostic reference levels (DRLs) are an important tool in the optimisation of clinical radiography. Although national DRLs are provided for many diagnostic procedures including dental intra-oral radiography, there are currently no national DRLs set for cephalometric radiography. In the absence of formal national DRLs, the Health Protection Agency (HPA) has previously published National Reference Doses (NRDs) covering a wide range of diagnostic X-ray examinations. The aim of this study was to determine provisional NRDs for cephalometric radiography. Methods: Measurements made by the Dental X-ray Protection Service (DXPS) of the HPA, as part of the cephalometric X-ray equipment testing service provided to dentists and dental trade companies throughout the UK, were used to derive provisional NRDs. Results: Dose-area product measurements were made on 42 X-ray sets. Third quartile dose-area product values for adult and child lateral cephalometric radiography were found to be 41 mGy cm 2 and 25 mGy cm 2, respectively, with individual measurements ranging from 3 mGy cm 2 to 108 mGy cm 2. Conclusion: This report proposes provisional NRDs of 40 mGy cm 2 and 25 mGy cm 2 for adult and child lateral cephalometric radiographs, respectively; these doses could be considered by employers when establishing their local DRLs.