Objectives: To develop image analysis software that can robustly and accurately measure the width of the inferior mandibular cortex on dental panoramic radiographs as an indicator of reduced bone mineral density (BMD). Methods: An Active Shape Model of the cortex was trained by expert annotation of 132 radiographs and used to locate the superior and inferior boundaries of the cortex automatically in a leave-one-out cross-validation test. Anatomical accuracy of the search is increased by employing a straightforward user interaction. Width was measured at 50 locations bilaterally between the antegonion and the mental foramen and averaged. Correlation between width and BMD (determined by DXA at the hip and spine) was measured and found to be highest in a region slightly medial to the antegonion – the “optimal” region. Taking osteopenia (T≤-1.0) as the categorical variable, we conducted ROC analysis using average width for both automatic and interactive search (tests 1 and 2) and “optimal” width (interactive search only – test 3). Results: Significant correlation (R=0.24, p<0.01) was found between BMD and average cortical width. ROC analysis gave Az values of 0.64, 0.66 and 0.71 in tests 1 2 and 3 respectively. Conclusions: We have developed an automatic image analysis method for measuring width of the inferior mandibular cortex. The average width between the antegonion and mental foramen correlates significantly with BMD. ROC analysis indicates that this method can contribute towards identification of osteopenia. The sensitivity and specificity of the measurement can be increased by the use of a straightforward user interaction. 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).