Aromatase inhibitors (AIs) might have a detrimental impact on bone health in breast cancer (BC) women. Denosumab has been shown to reduce the risk of fractures, but the appropriate time for starting is yet to be clearly defined. To evaluate the effects of early treatment with Denosumab (⩽ 12 months after starting AIs) compared to a delayed treatment in BC women. In this retrospective case-control study, we included medical records of BC post-menopausal women, treated with AIs therapy; they were divided as: study group (starting Denosumab ⩽ 12 months after AIs) and control group (> 12 months). At the baseline (T0) and at 18 months (T1), we evaluated the lumbar spine (LS) Tscore and femoral neck (FN) Tscore. Furthermore, at T1 we assessed the incident fragility fractures. Fifty-nine BC survivors (mean age: 61.5 ± 11.5 years) were included: 28 with Early Denosumab and 31 with Late Denosumab. At T1, the study group did not show any incident hip or vertebral fragility fracture, whereas the Late Denosumab group showed 2 incident hip fractures (6.5%) and 4 (12.9%) vertebral fragility fractures. Early Denosumab showed a significant positive effect on both LS (p= 0.044) and FN (p= 0.024) Tscore variations. Taken together, our findings suggest that an early start of Denosumab might be considered for the osteoporosis management in BC women undergoing AIs.