Bisphosphonates (BPs) are widely used for the management of hypercalcemia related to malignancy and bone metastases from breast cancer in Japan. We report a case of osteonecrosis of the jaw (ONJ) associated with a history of BPs therapy forthe management of bone metastases from breast cancer. A 69-year-old woman was referred to our department becaused of unhealed extraction sockets of the lower left premolar and first molar, which were removed at a dental clinic. CT scans of the mandible showed regions of mottled bone and sequestra, and a clinical diagnosis of ONJ was made. After conservative treatment with antibiotics and local minor curettage, the inflammatory symptoms almost completely disappeared. Dentists should be aware of this potentially serious complication in patients receiving long-term treatment with BPs.