This article aimed to estimate the prevalence of hepatitis C in Botafogo, a district of Bebedouro, São Paulo State, Brazil, and investigate possible risk factors. One individual over 18 years of age was selected from each household to answer a questionnaire on socio-demographic variables and factors associated with hepatitis C. Blood samples were also drawn for immunoenzymatic tests. Positive HCV-antibody samples were submitted to viral RNA detection. HCV prevalence was 8.8% (95%CI: 5.8-11.7), and independent variables associated with risk of infection were: male gender, time of local residence > 30 years, and history of injected medication using nondisposable material, sterilized by boiling. The high prevalence of hepatitis C infection in this relatively isolated rural population appears to result from previous exposure to injections with inadequately sterilized material, with some evidence suggesting a specific elderly pharmacy employee who customarily applied such injections and may have been a chronic HCV carrier.