Untreated waste water usage in agriculture is an important health-threatening issue which could affect both workers' and the public's health. In this study we researched hepatitis E infection in 46 of 57 farmers who used untreated waste water in agriculture. We compared them with 45 persons of the same socio-economic status and age. Anti-HEV seropositivity was 34.8% in the workers and 4.4% in the control group. We suggest that this type of irrigation is an important potential risk for hepatitis E infection.