Aim of the study was to evaluate, in a homogeneous group of patients with adrenal incidentalomas (AI), calcium-phosphorus metabolism alterations, bone mineral density (BMD) and the prevalence of vertebral fractures. We selected 46 patients with adrenal incidentalomas (26M, 20F; age: M = 61 +/- 14, F = 65 +/- 10 years, BMI: M = 26.2 +/- 4 Kg/m2, F = 28.8 +/- 4 Kg/m2) compared with 84 normal subjects (NS) (44M, 40F; age: M = 60 +/- 10, F = 62 +/- 8 years; BMI: M = 27 +/- 2 Kg/m2, F = 28.1 +/- 4.5 Kg/m2). In all subjects we estimated calcium-phosphorus parameters. Our results showed that in 46 patients with AI there were a significant reduction of BMD-LS (0.915 +/- 0.176 g/cm2; p = 0.01) and of BMD-FN (0.710 +/- 0.129; p = 0.034) respect to those of NS (respectively: 0.994 +/- 0.14 9 g/cm2; 0.758 +/- 0.117 g/cm2). BMD-LS of the 20 women with AI (0.864 +/- 0.157 g/cm2, p = 0.01) was significantly reduced compared with the 40 female normal subjects (0.904 +/- 0.148 g/cm2); BMD-LS of the 26 men with AI (0.967 +/- 0.187 g/cm2; p = 0.048) was significantly reduced compared with the male normal subjects (1.048 +/- 0.133 r/cm2; p = 0.048). The MXA showed vertebral fractures in 15 (75%) of 20 patients with AI (2 patients were osteoporotic, 9 osteopenic and 4 normal at the MXA scans). In 20 women with AI, compared with female NS, we found a significant reduction of serum 25 OH D3 (p = 0.024) levels and a significant increase of plasma i-PTH (P = 0.04) value; and we found a negative correlation between plasma i-PTH and 25 OH D3 values (r = -0.451; p > 0.045). In conclusion, we demonstrated that patients with non-functioning adrenal incidentalomas present calcium-phosphorus metabolism alterations, associated at a reduction of BMD and an increase of vertebral fractures.