Osteomyelitis of the jaws is a challenging disease for the clinicians and the patients despite many advances in the diagnosis and treatment. It was a common and dreaded disease in the past because of its prolonged course and uncertainty of outcome. It is an interesting fact to know that the oral cavity is among the most biologically dynamic tissues of human body. Any adverse change arising from any immunosuppressive systemic disease will readily manifest itself in the oral cavity. Osteomyelitis is not an exception to this. Thus, a careful evaluation of an apparently healthy individual presenting with a jaw swelling that may be associated with odontogenic infection must always be emphasized. This particular chapter will provide a brief introduction to the Osteomyelitis of the jaws so as to orient the readers towards the disease, its etiopathogenesis and clinicopathological features.