Background and Aims: Healthcare workers (HCW) have an increased risk of exposure to infectious diseases and are a potential source of infections for their patients. The Lao People's Democratic Republic (Lao PDR) has no national policy regarding HCW vaccinations and routine vaccination coverage is low within the general population. This cross-sectional serostudy determines the level of exposure and risk of infection in Lao HCW against 6 vaccine preventable diseases and hepatitis C. Methods: 1128 HCWwere recruited from 3 central, 2 provincial and 8 district hospitals. Sera were tested by ELISA for the presence of antibodies and antigens to hepatitis B, hepatitis C, measles, rubella, varicella zoster, tetanus and diphtheria. Results: Only 53.1%of the HCW had protective anti-hepatitis B surface antigen antibodies (anti-HBs) with 48.8% having anti-hepatitis B core antibodies (anti-HBc), indicating previous exposure and 8.0% were hepatitis B surface antigen carriers. 3.9% were hepatitis C seropositive. Measles and rubella antibodies were detected in 95.4% and 86.2% of the HCW, with 11.9% of females being unprotected against rubella. Antibodies against varicella zoster, tetanus and diphtheria were detected in 95%, 78.8% and 55.3%, respectively. Seroprevalence varied according to age, gender and number of children. Conclusion: An unacceptably high proportion of Lao HCW remain susceptible to infection with hepatitis B, diphtheria, tetanus and rubella. Furthermore, a high number of healthcare workers are chronically infected with hepatitis B and C viruses. These data emphasize the need for a robust HCW vaccination policy in addition to increased awareness within this subpopulation.