In order to examine the prevalence of HIV infection and associated risk factors amongst Spanish female prostitutes a multicentre (n = 22) cross-sectional study was conducted between November 1989 and January 1991. Data collected included socioeconomic characteristics, sexual behavior and health status together with blood samples. A total of 1633 prostitutes were recruited into the study. Of these, 1433 (87.8%) consented to blood samples being taken and 180 (12.6%) were HIV positive. HIV seroprevalence was 54.7% for intravenous drug users (IVDUs) versus 3.7% for non-IVDUs. Previous imprisonment, hepatitis B and a partner who was an IVDU were significant predictors of HIV infection according to multivariate logistic regression models.