BACKGROUND: Bisphosphonate use is associated with atypical non-traumatic fractures, which are most commonly seen in the femur. CASE PRESENTATION: We report a 63-year-old postmenopausal woman who presented acutely with progressively worsening lumbar pain radiating to her left hip for 10 days. There was no antecedent trauma. On examination, the patient could not bear weight on her left leg due to the severity of the pain. Radiography and computed tomography of the pelvis demonstrated an iliac wing fracture which was treated conservatively. The patient had a significant past medical history of breast cancer and intense bisphosphonate use for several years which was discontinued 3 years previously. No discrete bone lesion was seen at the fracture site on computed tomography, and there was no evidence of metastatic disease elsewhere. A dual-energy X-ray absorptiometry scan showed the lowest bone mineral density T-score of - 1.2. A diagnosis of an atypical fracture related to long-term bisphosphonate therapy was made. CONCLUSION: To the best of our knowledge, this is the first reported case of an isolated iliac wing fracture associated with long-term bisphosphonate therapy in the literature. Whilst the incidence of such fractures is exceedingly rare, it is an important differential in patients with atypical fractures on long-term bisphosphonates.