Introduction: Bisphosphonates (BPs) are powerful drugs that inhibit bone metabolism. Adverse side effects are rare but potentially severe such as bisphosphonate-related osteonecrosis of the jaw (BRONJ). To date, research has primarily focused on the development and progression of BRONJ in cancer patients with bone metastasis, who have received high dosages of BPs intravenously. However, a potential dilemma may arise from a far larger cohort, namely the millions of osteoporosis patients on long-term oral BP therapy. Patients and methods: This current study assessed 470 cases of BRONJ diagnosed between 2004 and 2008 at eleven different European clinical centres and has resulted in the identification of a considerable cohort of osteoporosis patients suffering from BRONJ. Each patient was clinically examined and a detailed medical history was raised. Results: In total, 37/470 cases (7.8%) were associated with oral BP therapy due to osteoporosis. The majority (57%) of affected individuals did not have any risk factors for BRONJ as defined by the American Association of Oral and Maxillofacial Surgery. The average duration of BP intake of patients without risk factors was longer and the respective patients were older compared to patients with risk factors, but no statistical significant difference was found. In 78% of patients the duration of oral BP therapy exceeded 3 years prior to BRONJ diagnosis.