Background Breast cancer is the most common cancer and the leading cause of cancer–related deaths among women worldwide. The annual global incidence of breast cancer is estimated to be >1.3 million cases and approximately 465,000 women die of this disease every year. Osteoporosis is a common chronic problem in postmenopausal women that increases the risk for spinal compression fractures and fractures of the femoral neck, causing life–threatening complications. Cancer–induced osteoporosis is a long–term complication associated with cancer therapy that can directly or indirectly affect bone metabolism. Objective To estimate the bone mineral density (BMD) before and after the treatment in patients of carcinoma breast Material & Method: This prospective clinical study involves 27 histopathologically proven cases of carcinoma breast patients which were conducted during October 2017 to August 2018 to estimate the bone mineral density (BMD) before and after the treatment in patients of carcinoma breast.The categorical clinical characteristics between the two treatments are compared using chi–square test. Result: in this study the Majority of the patients had stage IIIB and IIB disease 12 out of 27(44.4%) patients presented with IIIB disease, 9 out of 27(33.3%) belongs to stage IIB, 4 out of 27 (14.8) were in IIIA, 3 patients out of 27(11.1%) had IIIC disease. The BMD measured at lumbar region included L1 to L4 vertebrae with population matched T–scores and Z–scores. In all 27 patients, the mean BMD at L1, L2, L3 and L4 were 0.885, 0.923, 0.995 and 1.00 gm/cm² respectively. Similarly, among patients completing treatment, mean BMD at L1, L2, L3 and L4 were 0.843, 0.810, 0.867 and 0.911 gm/cm² respectively. The total lumbar spine BMD (L1–L4) was 0.912 ± 0.141 gm/cm² in all 27 patients, whereas it was 0.812±0.879 gm/cm² in patients completing treatment. The maximum BMD value was at L3 (1.90gm/cm²) and minimum value was at L1 (0.641 gm/cm²). The mean lumbar spine BMD values were observed slightly higher among total patients at all sites i.e. L1, L2, L3, L4 and L1–L4, compared to the completed treatment group. Conclusion In our study we found that most of the patients with newly diagnosed carcinoma breast had pre–existing osteopenia and osteoporosis, at both Lumbar Spine and Hip regions. The maximum BMD value was at L3 (1.90gm/cm²) and minimum value was at L1 (0.641 gm/cm²). In Hip region the maximum BMD value was found at wards (1.19gm/cm²) and minimum value was at Trochanter (1.0 gm/cm²).In patients completing chemo–radiotherapy, majority of the premenopausal patients were osteopenic, whereas majority of the postmenopausal patients were osteoporotic