Infection with Opisthorchis viverrini (OV) due to eating certain traditional freshwater fish dishes is the principalrisk factor for cholangiocarcinoma in Northeast Thailand where the infection is endemic and the incidence of thisform of primary liver cancer has been the highest in the world. This paper is the second report of a prospectiveresearch project to monitor the impacts of a national liver fluke control programme in a rural community ofNortheast Thailand. A sample of 684 villagers aged 20-65 years completed an interview questionnaire and weretested for infection using the Kato thick smear technique. The questionnaire was designed for the exploration ofassociations between OV infection, previous treatment with praziquantel, and knowledge and beliefs about thedrug. The data were analysed using descriptive statistics and multiple logistic regression. The overall prevalenceof OV infection was 37.2% and was highest in the 20-35 year age group, in those with a university degree and inthose employed in the government sector. As many as 91.8% reported eating fish dishes known to place them atrisk of infection. In the multiple regression analysis, previous use of praziquantel and lack of knowledge aboutwhether or not the drug has a protective effect against re-infection were the only factors related to OV infection(ORadj= 2.31, 95%CI =1.40-3.79 and ORadj= 1.95, 95%CI= 1.24-3.05). The findings were discussed in terms ofthe possibly unwise dependency on praziquantel as a primary element in a control programme.