Background: Hepatitis B virus (HBV) is a member of the family of the hepadna viridae, which is infectious for humans and a few animal species. At the beginning of the third millennium, HBV remains a major public health problem globally with more than one third of worlds' population infected.Of these, 350–400 million suffer from chronic HBV infection. This infection has been identified as one of the most important causes of liver failure and hepatocellular carcinoma (HCC). According to the world health organization (WHO), more than 50 million cases of acute hepatitis B infection are reported annually with 5–10% of adults and up to 90% of infants becoming chronically infected. From the dangers that face the dentist and auxiliary dentist is infection transmission. This study was performed to search about the knowledge of viral hepatitis and ways to prevent transmission and protect the dentists from viral hepatitis. Methods: We conducted a descriptive cross-sectional study on dentists and dental auxiliaries working in private dental clinics in Al-Qassim city, Saudi Arabia. The total sample obtained was 98 dentists and dental auxiliaries. Results: Nearly (36.3%) aged from 25-30 years old, (31.6%) aged from 31-35 years old, (22.4%) aged from 20-24 years old, and (9.2%) above 35 years old. The majority were dental hygienists and dental graduates, (46.9%) and (40.8%), respectively. Almost the majority of participants (99%) had at least some knowledge about viral hepatitis. (52%) thought hepatitis B vaccine can be given as post-exposure prophylaxis.  Conclusion: In conclusion, we need to emphasize on the preventive measures of transmission of viral hepatitis among dentistry clinical field doctors.