Résumé : Jaws osteonecrosis were, in most cases, caused by external irradiation. It was otherwise a rare occurrence. However, bisphosphonates have recently been associated with osteonecrosis of the mandible or the maxilla. Bisphosphonates are widely used in the treatment of osteoporosis, multiple myeloma and osteolytic bone metastases. They inhibit bone resorption by osteoclasts and disrupt the bone turnover. The so-caused bone expositions are painful and prone to surinfection. Even after cessation of the bisphosphonates, the results of medical and surgical treatment are very inconsistent. A thorough dental check-up is recommended before initiating a course of bisphosphonates.