Little information is available regarding human immunodeficiency virus (HIV) infection among female sex workers (FSW) in Burkina Faso, West Africa. A cross-sectional study was conducted in Ouagadougou and Bobo-Dioulasso, the 2 largest cities of the country, to determine the prevalence of HIV infection and other sexually transmitted diseases (STDs) among FSWs, and to investigate the factors which were associated with HIV infection in this population. From October to November 1994, 426 FSWs were recruited. The method of anonymous and unlinked HIV screening recommended by the World Health Organization (WHO) was used. The overall HIV seroprevalence was 58.2% (95% confidence interval: 53.4-62.9) and 52.6% of FSWs had at least one STD agent. The most common STDs were trichomoniasis (23%), syphilis (15%) and gonorrhoea (13%). In a logistic regression analysis, risk factors for HIV infection were high gravidity (> or = 2 pregnancies), low perception of personal risk of HIV infection, syphilis and the presence of genital warts. These results suggest that FSWs in Burkina Faso need better information about HIV transmission and prevention and then need better access to STD detection and management services.