The author studied age and sex distribution, etiology, affected site and several radiographic features of osteomyelitis of the jaw. And radiologic classification of osteomyelitis was also done. The material consisted of 118 males and 96 females examined and/or treated under the diagnosis of osteomyelitis during past 11 years (1970-1980.6) in SNUDH. The obtained results were as followings. 1. The incidence is the highest in teenages(22.9%) and the lowest in seventies. (2.8%). 2. 199 cases were found in lower jaw, and 15 cases in upper jaw. 30.8% of all cases were located at the posterior portion of mandibular body comprising alveolar region. 3. Radiographic examination of osteolytic lesion revealed that 21. 5% of all patients had periapical and alveolar bone rarefaction combined with osteoporotic changes and that in most of patients two or more of the above described changes were present at the same time. 4. Sclerotic lesions were seen in 62.2 % of all patients and 21.5% of sclerotic lesion were diffuse or homogenuous type. 5. Based on the radiologic study, classification of the osteomyelitis of the jaw was made. Loclized osteolytic type was the highest in incidence (38.8%) and localized sclerotic type was the lowest (7.0%)