The study aimed at monitoring the immune status of health care workers (HCWs) of a tertiary hospital after accidental exposure to Hepatitis B virus (HBV). Methods: Between January 2004 and December 2006, 353 cases of exposure to Hepatitis B virus were reported. The HBV-exposed HCWs were required to undergo follow-up serum tests to analyze their immune status one year after the exposure. The obtained data were then analyzed to determine the incidence of exposure and of sero-conversion. Results: In this hospital, an average of 9.8 cases of Hepatitis B exposure among HCWs was reported in a month. Follow-up tests conducted after exposure revealed that 90.4% of the HBVexposed HCWs were positive for Hepatitis B antibody and 66.9% of the HBV-exposed HCWs were reported to have antibody levels exceeding 10 mIU/mL. Results of serum tests for the HBV antigen conducted one year after exposure were negative for all the exposed HCWs. Conclusion: Among the 79.6% of the HCWs who underwent serum tests one year after exposure the HBV sero-conversion rate was 0.0%. However, a further investigation in the form of longterm and multi-center studies is required to confirm this result. Furthermore, an active system should be established to ensure that all exposed HCWs undergo follow-up serum tests.