Osteopetrosis (marble bone disease, Albers-Schönberg disease) is in the majority of the cases an inherited disorder, which is caused by a considerably decreased function of bone resorbing cells (osteoclasts). Through constant accumulation of bone tissues, the microarchitecture of the bony structures get highly impaired, whereby the mechanical stability of the bone declines, leading to frequent bone fractures. Different variations of autosomal dominant and autosomal recessive inherited disorders are distinguishable, which are highly distinctive in their onset, their clinical manifestation and in the progression of the disease. A 58-year-old patient, who was referred to our clinics after unsuccessful treatment at a hospital in Libya, is presented. Following an existing osteopetrosis this patient developed a massive osteomyelitis in the maxilla and mandible with abscess, extra-oral fistula, and a widespread impairment of the soft tissues. After clinical examination of the soft tissue, vast osseous lesions in terms of acute osteomyelitis were diagnosed, based on the computer tomography (CT) and the digital volume tomography (DVT) findings. Major parts of the maxilla and the mandible and both zygomatic bones were affected. Phlegmonous involvement of all surrounding soft tissues was present. As additional findings characteristic signs of an autosomal dominant inherited osteopetrosis were found in parts of the craniofacial bone as well as the cervical spine ("rugger-jersey-spine"). Laboratory-chemical results showed a characteristic decrease of the Calcium level. The surgical rehabilitation based on a removal of the diseased tissues proved to be challenging due to the broad extension. In some parts centimetre-sized sequesters including the teeth were extracted. The reduced healing tendency of the osseous structure led to a difficult and prolonged progression of the disease. With several surgical interventions and intensive medical adjunctive therapy the wounds could finally heal, however, extreme mandibular and mid-facial defect sites were still present. An Osteomyelitis resulting from an osteopetrosis is usually not as characteristic symptom or complication of this disease. However, if it develops,it may make the surgical treatment and management extremely difficult. The knowledge of the pathogenesis of the underlying disease is an important prerequisite for an adequate planning of the therapy and for the conduct of a successful treatment of the operative steps. Keywords: Osteopetrosis, Osteomyelitis, Albers-Schönberg Disease