Medical personnek are one of several groups that have been reported to have a high incidence of hepatiris B. It is also thought that the occurrence rate of hepatitis B surface antigen(HBsAg), aserologic marker for hepatitis B virus(HBV), is expected to be high in the dental personnel who are frequently exposed to the blood and saliva of the patients. Although many studies have been done to determine the HBsAg status of virus groups, limited investigations have been performed on dental personnel, especially in this country. The main purpose of this study was to identify HBsAg positivity among dental students, interns, and residents who would be expected to be a high risk group of hepatitis B infection. Screening test for HBsAg of a dental school population was performed by indirect hemagglutination(IHA)in 1982. The results were as follows : 1. Thirty four out of a total 362 persons(9.4%)tested in the study had positive response for HBsAg in their serum samples. 2. Twenty seven out of 320 dental students(8.4%)had positive for HBsAg, and in Senior class 12 out of 82 dental students (14.6%)had positive response that was the highest incidence among dental students group. 3. Seven out of 42 interns and residents(16.7%)had positive for HBsAg, and it was the highest incidence in this dental school population.