This is a clinical study on 235 inpatients who sustained a total of 350 mandibular fractures and who were treated in our department during the period of Oug., 1989 through Dec., 1993. The results obtained are as follows: l. The mumber of patients has not been increased year after year. In respect of incidence, there were the highest frequency as 67 patients (28.5% ) in 1991 and the least frequency as 16 patients (6.8% ) in 1989 and the highest frequency as 28 patients (11.9%) in October and the least frequncy as 12 patients (52%) in February. 2. The age frequency was the highest in the second decade (30.6%), The youngest patient was 8 months and the eldest patient was 80 years and mean age was 27.8 years. The ratio of men to Wemen was 4:l. 3. The most frequent cause was fall down as 86 patients (36.6%) and the next was fist blow 4 as 75 patients (31.9%), traffic accident as 56 patients (23.9%) in order. The most common location was symphysis as 141 numbers (40.3%) and the next was condyle as 96 numbers (27.4%), angle as 94 numbers (26.8%), body as 14 numbers (4.0%) in order. The sum of fracture sites were 350 and there were 1.49 fracture sites per one patient and multiple fractures occured in 100 patients (40.5%) of the 235 patients. The ratio of Left to Right except for symphysis was l.71:l. 5. Among the 333 associated injuries, facial laceration was 186 (57.9%) and tooth injury was 58 (24.7%) and extremity was 31 (13.2%). 6. Among the 350 mandibular fractures, complications after treatment occured in 51 (14.6%) and infection as 20 (5.7%) was the most frequent complication. 7. In respect of treatment of mandibular fracture, close reduction was 64 patients (27.2%) and open reduction was l64 patients (69.8%) and other were 7 patients (3.0%) of all and so open reduction was the most common in type of treatment.