Osteomyelitis is an infection in the bone including the periosteum, medullary portion of the bone and cortical bone. Osteomyelitis of the jaw much more commonly involves the mandible than the maxilla due to less profuse nature of blood supply and the density of the cortical bone. Osteomyelitis can be classified as suppurative and nonsuppurative. The acute, chronic and infantile osteomyelitis are all considered suppurative. Also, chronic suppurative osteomyelitis can be classified as primary or secondary. Nonsuppurative osteomyelitis can be divided into chronic sclerosing osteomyelitis, Garré’s sclerosing osteomyelitis, actinomycotic osteomyelitis, and radiation osteomyelitis and necrosis. The classification recognizes focal sclerosing and diffuse sclerosing osteomyelitis as well, which are considered to be the types of chronic sclerosing osteomyelitis. Osteomyelitis can be caused by bacteria, fungi or mycobacteria. Aerobic streptococci and Staphylococcus aureus and epidermidis are responsible for the majority of the cases of osteomyelitis of the jaw. Trauma is the second most common cause of osteomyelitis. Radiographic changes of the bone can be seen 4-8 days or 3 weeks after the onset of the infection. That is why the early diagnosis of osteomyelitis is difficult and in the beginning of the disease diagnosis based on anamnesis and clinical findings. The onset of acute osteomyelitis includes prodromal symptoms, pain i pus accumulation. Those symptoms are weak or nonexistent in chronic forms of the disease. Magnetic resonance imaging and bone scintigraphy have been proven useful in early diagnosis of osteomyelitis because changes are seen as early as 3 days after the onset of the osteomyelitis symptoms. The treatment of osteomyelitis consists primarily of long-term antibiotic therapy, most commonly high-dose intravenous antibiotic therapy. Antibiotic therapy depends on antibiotic sensitivity, testing and surgical phase of the treatment. The most valuable antibiotic in treatment of osteomyelitis is penicillin or clindamycin in case a patient is allergic to penicillin. The surgical treatment includes sequestrectomy. In some severe cases, extensive surgical treatment is necessary, such as decortication of the mandible or resection and reconstruction. Sometimes patients have underlying disease which can alternate their immune system and make them susceptible to infections such as osteomyelitis. In those cases, it is necessary to treat both osteomyelitis and the underlying disease.