Three groups of Copenhagen municipality male employees-77 sewer workers, 81 gardeners, and 79 clerks-matched for age and duration of employment, were studied for clinical and serological evidence of infection with viral hepatitis types A and B and pathogenic leptospires. "Antibody against hepatitis A virus" (anti-HAV) was found significantly more often among sewer workers (80.5%), than among gardeners (60.5%) or clerks (48.1%). The anti-HAV prevalence rates correlated with age rather than duration of employment. Of all the 11 cases of jaundice reported, only 3 cases (sewer workers) occurred while employed for the city. One case of the 11 resulted from leptospirosis. Anti-HAV was detected in the other 10 subjects and was assumed to be of etiological importance. Hepatitis B serological markers were similar in each group. It is concluded that exposure to metropolitan sewage provides a limited risk of enteric infections, such as hepatitis A, while the hepatitis B virus apparently is not successfully transmitted by this route.