Objectives: To determine the diagnostic validity of mandibular and maxillary bone density, measured between the premolars (mm Aleq) in detecting osteoporosis at the hip or lumbar spine. Methods: Female subjects between 45 and 70 years of age, were recruited from 4 European centres. They underwent dual x-ray energy absorptiometry of the hip and lumber spine, to provide a gold standard diagnosis of osteoporosis. In addition, intra-oral radiography of upper and lower right premolar region was performed, using an aluminum wedge as a densitometric reference. Jaw bone density in 4 selected regions of interest (ROI) was determined using dedicated software Osteop (Nackaerts et al 2005**). Two ROIs were determined between the upper premolar teeth and another 2 between the lower premolars. 5 observers performed the analysis. Intra- and inter-observer differences and ROC curves were analyzed. Results: Results from 660 subjects (mean age 54.8y; sd 6.19) were suitable for analysis. 136 of these subjects were classified as having osteoporosis. For ROC analysis, measurement data from all observers were averaged, since there was no significant inter-observer difference. Az values as well as 95% confidence intervals are shown in the table: Detecting osteoporosis at any site (spine, hip, femoral neck): ROI1 upper jaw Az 0.691 (0.653 to 0.726) ROI2 upper jaw Az 0.708 (0.671 to 0.743) ROI1 lower jaw Az 0.709 (0.672 o 0.745) ROI2 lower jaw Az 0.702 (0.655 to 0.738) None of the differences in Az between sites was statistically significant (p always > >0.05). Conclusions: Density of the premolar region expressed in mm Aleq is a fair indication for the presence of osteoporosis. More extensive analysis of the OSTEODENT results might reveal an even better predictive tool for osteoporosis screening. **Nackaerts O, Jacobs R, Pillen M, Engelen L, Gijbels F, Devlin H, Lindh C, Nicopolou-Karayianni K, van der Stelt P, Horner K. Accuracy and precision of a densitometric tool for jaw bone. DentoMaxilloFacial Radiology. In press This work was supported by a research and technological development project grant from the European Commission FP5 'Quality of Life and Management of Living Resources' (QLK6-2002-02243).