BACKGROUND: The main occupational hazard of wastewater workers (WWs) is the direct exposure to the variety of infectious agents present in sewage material, with hepatitis A virus (HAV) being the most frequent one. Most epidemiological studies have shown a higher risk of hepatitis A among WWs, although some studies have produced conflicting evidence. AIMS: To evaluate the hypothesis of increased risk of HAV infection in WWs. METHODS: The prevalence of antibodies to HAV in 869 WWs was compared to 311 other subjects and analysed to detect the main potentially confounding variables. RESULTS: Univariate analysis demonstrated that occupational exposure to sewage was not significantly associated with the prevalence of anti-HAV(+). The anti-HAV(+) prevalence was strongly associated with age and shellfish consumption (P < 0.05) when the subcategories of workers were examined separately (WWs and control group) and jointly. In the logistic regression model, a significant association between anti-HAV(+) prevalence and duration of employment (P < 0.05) was found. The interaction term (age x duration of employment) was significant (P < 0.001) when included in the logistic model. CONCLUSIONS: This study shows that working in a wastewater treatment plant does not seem to be related to a greater prevalence of antibodies to hepatitis A. Moreover, the relative risk of HAV infection among WWs seems to be correlated with low anti-HAV(+) prevalence in the general population.