Objective: The consequences of aging often involve the risk of osteoporosis, leading to an impaired quality of life of the elderly patients specially postmenopausal women. Osteoporosis accounts 0.83% of non-communicable disease globally having significant health and economic impact. The aim of this study was to evaluate and correlate the changes of mandibular cortical bone with bone mineral density (BMD) in postmenopausal osteoporotic patient. Materials and Methods: 300 postmenopausal osteoporotic patients included in these study. All patients were evaluated by dual-energy X-ray absorptiometry for BMD, and orthopantomograph (OPG). Mandibular cortical index (MCI) was seen from OPG categorized into C1, C2, and C3 as the appearance of the mandibular inferior cortex distal to the mental foramen. The criteria of C1 endosteal margin of the cortex is even sharp on both sides of the mandible, C2 endosteal margin has semilunar defects (resorptive cavities) with cortical residues one to three layers thick on one or both sides, C3 endosteal margin consists of thick cortical residues and is clearly porous. Results: The result of this study was showed that mean femoral neck T-score in C1 group and C2 were 2.26 ± 0.81 versus 2.88 ± 0.73, respectively, (P < 0.05) that was statistically significant, lumbar spine T-score in C1 group and C2 were 2.49 ± 0.96 and 2.62 ± 0.72, respectively, (P > 0.05) was not statistically significant and mean femoral neck T-score in C2 group and C3 were 2.88 ± 0.73 vs 2.49 ± 0.96, respectively, (P > 0.05) that was not statistically significant, lumbar spine T-score in C2 group and C3 were 2.62 ± 0.72 and 3.21 ± 1.18, respectively, (P < 0.05) was statistically significant. MCI-C3 is almost perfect indicator of osteoporosis. Conclusion: Changes of MCI are correlated significantly (P < 0.01) well with osteoporosis variable. Simple, low-cost investigation OPG determining MCI may be helpful as diagnostic tool for osteoporosis.