Disturbances of the interrelationship among the host, environment, microorganism will cause the infection clinically. Infection can be classified into bacterial, viral, fungal origin. Bacterial infection is most common due to dental caries, periodontal disease. These infections have the potential to spread via the fascial spaces in the head and neck region. We have undertaken clinical studies on infections in the oral and maxillofacial regions by analysing 78 hospitalized patients in the Dept. of Oral and Maxillofacial Surgery, Dong-A University Hospital from 1994 to 1997. The results were as fellows : 1. Odontogenlc infections were most common with the incidence of 84.6% , 2. Considering the number of involved space, single space was 83.3%, double or more space was 16.6%. The most common fascial space involved was submandibular space and followed by buccal space. 3. The most causative organism isolated from the pus cultures was streptococci group 35.4% . 4. Antibiotics were administrated in all cases, and surgical incision and drainage was performed in 87.2%. 5. Combined administration of penicillin and aminoglycoside was most common in 34.6% 6. 7 cases were diagnosed as Ludwig's angina and tracheostomy was done in 2 cases of them.