The prevalences of Opisthorchis viverrini infection in the villages on the banks of rivers and those far from the rivers were studied in Loei and Nong Khai Provinces in Thailand. Most of the people examined in the present study were agriculturalists. The overall prevalence of O. viverrini infection was 41.3%. The prevalence of infection in males and in females in the villages far from the rivers were 52.6% and 51.7%, respectively, while the percent of people in the villages on the banks with infection were 27.9% and 21.7%, respectively. Prevalence of infection among the people residing far from the rivers was higher than those residing on the banks. This was observed despite the higher recording of raw fish consumption in villages on the banks. Infection level increased sharply in the age-group 6-10 years old among people residing far from the rivers. High prevalences of infection were observed in age groups from 11 to 50 years. Both types of villages had a similar proportion of houses with sanitary latrines.