Abstract: The aim of this study is to assess the bone mineral density (BMD) and T-score reference values in a population from 18 to 95 years old in Lombardy region, Italy. This study also investigates the association between BMD values and body mass index (BMI) divided by gender and age. The evaluation of BMD was analyzed by T-score and BMD in each site, femur, and column. A total of 10,503 patients (9,627 females and 876 males, 65.04±12.18 years) have been enrolled in this study. The women hip femur reference values associated with a situation of osteopenia highlighted in-line with the class of age of 45 to 55 years were: mean values: −1.3132 T-score; 95% confidence interval (CI): −1.3600 to −1.2664 and of osteoporosis from the class of age 85 to 95 years, mean values: −2.6591 T-score, 95% CI: −2.7703 to −2.5479. The men hip femur reference values associated with a situation of osteopenia highlighted in-line with the class of age of 45 to 55 years were: mean values: 1.2986 T-score; 95% CI: −1.5454 to −1.0518. A positive association between BMI and the two sites of BMD was recorded (p > .05). This study provides an Italian overview of national and regional reference values about the BMD and T-score values divided by age and gender as reference values for clinicians for a correct assessment and monitoring.