Background: Diagnosing bisphosphonates induced atypical femoral fracture (AFF) in patient with bony metastasis can be challenging and overlooked. Case Report: We present a case of atypical sub-trochanteric femoral fracture in a patient treated successively with Zoledronic acid and Denosumab with known skeletal metastasis from breast carcinoma. The fracture was fixed using cephalo-medullary nail. Conclusion: Clinical oncologists should consider the possibility of AFFs in patients on long-term bisphosphonates treatment for bone metastases. Inability to identify those lesions as different from original malignant condition can lead to delayed diagnosis, sub-optimal treatment and missing opportunity to prevent progression of incomplete to complete fractures.