Since the introduction of bisphosphonates to treat diseases that affect 
remodelling of bone, increasing numbers of patients with bisphosphonate-related 
osteonecrosis of the jaws have been reported; the number is currently unknown. 
Recently anti-RANKL agents (receptor activator of nuclear factor-kappaB ligand) 
such as denosumab (Prolia, Amgen Inc., California, USA) that have a similar mode 
of action to bisphosphonates have been introduced to treat such diseases. We 
report a case of osteonecrosis that was induced by anti-RANKL therapy. To our 
knowledge this is the first case to have been induced by these agents.