During the years 2000 to 2004, of 248 serologically confirmed cases of Crimean-Congo hemorrhagic fever (CCHF) that occurred in several parts of Iran, 169 were reported from Sistan-va-Baluchestan province. To assess the seroprevalence of CCHF virus infection within the Zahedan and Zabol districts of the Sistan-va-Baluchestan province in Iran, 300 subjects were sampled from the general population. In addition to blood sampling, a questionnaire was completed for every subject. All but just 3 of our 300 sampled subjects participated in blood sampling, and just 7 out of the 297 serum samples were found to be IgG ELISA positive. The point estimate of the seroprevalence was 0.024 (95% confidence interval: 0.003-0.044). A history of keeping livestock in houses (even for short periods) showed an association with seropositivity (P = 0.018). It seems that even occasional contact with livestock could be effective in transmission of the virus.