This is a clinical study on patients who had visitied the Emergency Room of Pusan National University Hospital and then been treated in the Department of Oral and Maxillofacial Surgery during recent 5 years, from 1992 to 1996. The results were as follow ; 1. The total number of patients was 2,680 and the ratio of male to female was 1.96:1, The highest monthly incidence was shown in September(12.1%) and October(10.5%) and the age distribution peaks was the third decade(24.3%), followed by the first(23.1%) and the fourth decade(17.2%). 2. Soft tissue injury group(29.1%) was the most prevalent, followed by tooth injury group(16.1%), facial bone injury group (16.0%), toothache group(11.2%), socket bleeding group(11.1%), infection group(9.8%) and TMJ dislocation group(5.9%). 3. The percentage of in-patients and out-patient were 21.6% and 78.4%, respectively. The frequent causes of admission were facial bone fracture(73.8%), infection(20.8%) and soft tissue injury(4.8%) in order. However, soft tissue injury was the most frequent cause in out-patient, followed by tooth injury(20.5%), toothache(14.3%), socket bleeding(14.2%) and TMJ dislocation(7.6%). 4. In the facial bone injury group, the mandibular fractures(70.6%) showed the highest incidence, followed by zygomatic bone and arch fractures(7.5%), maxillary bone fractures(4.0%) and nasal bone fractures(4.0%). 5. In the mandibular bone fracture, the most common location was symphysis(36.7%), followed by the mandibular angles(33.1%) and the condyles(21.8%). 6. The common causes of facial bone fractures were violence, fall and traffic accident in order. 7. The common causes of soft tissue injury were fall down, fight and traffic accident in order and the highest incidence was observed in infants before the age of 10 years(44.0%). 8. In the group of tooth injury, tooth luxation(38.5%) showed the highest incidence followed by tooth fracture(33.2%) and tooth loss(17.1%). The common causes of tooth injury were fall, fight and traffic accident in order. 9. In infected patients group, the ratio of in-patients to out-patients was 1 : 1.28, Buccal(24,7%) and infraorbital space abscess(23.3%) showed the highest incidence. 10. The pain caused by dental caries(39.0%) and pericoronitis(26.6%) showed high incidence in the toothache group. 11. The high incidence was observed during third(34.0%) and fourth (24.5%) decades in TMJ dislocation group. 12. In the group of socket bleeding patients, 92% was post-operative hemorrhage and 8% was accompanied with other systemic hemorrhagic diseases.