OBJECTIVE: To determine prevalence of HIV infection in a cohort of female sex workers in Cameroon, and to describe characteristics associated with HIV infection in this population. METHODS: In a cross sectional study, 2260 female sex workers in Cameroon were interviewed and screened for HIV serostatus. A standardised questionnaire was used to collect information on sociodemographic characteristics and sexual and health behaviours. RESULTS: Seropositive participants (18%) were more likely to be over age 25, have four or more children, live in Yaoundé or Douala for 5 years or less, solicit clients in their homes or on the street, have a low educational level, earn a weekly income of less than $24, and have no other occupation outside of sex work. A logistic regression model of selected sociodemographic characteristics indicated that women at particularly high odds of HIV infection were older, poorer, and new immigrants to their city of residence. CONCLUSION: This seroprevalence study found a lower HIV prevalence than had been previously reported. Although our results are different, this group is still at much higher risk of HIV infection than the population as a whole.