To assess the prevalence of and risk factors associated with HIV infection in European female sex workers, particularly sexual risk factors. Multicentre cross-sectional study performed in nine European countries. Female sex workers voluntarily enrolled between September 1990 and November 1991. Face-to-face interviews were conducted in various settings (health care, prostitute organizations, outreach) to collect information on over 150 behavioural, health and sociodemographic variables. Enrollment of intravenous drug users (IVDU) was limited to a maximum of 25% of the total sample. The HIV-1 and HIV-2 antibody status of blood or saliva samples was tested using enzyme-linked immunosorbent assay and confirmed by Western blot. Eight hundred and sixty-six (91.6%) of the 945 interviewees provided blood (n = 824) or saliva (n = 42) samples. HIV seroprevalence was 5.3% [44 HIV-1-positives and two HIV-2-positives (from Lisbon)] overall, 31.8% (35 out of 110) in IVDU and 1.5% (11 out of 756) in non-IVDU [odds ratio (OR), 31.6; P < 0.001]. Lack of condom use (P = 0.002, test for trend) and previous ulcerative sexually transmitted disease (OR, 3.6; P = 0.06) were associated (on logistic regression) with HIV infection in both IVDU and non-IVDU. Previous hepatitis B (OR, 13.8; P = 0.02) and needle-sharing (OR, 4.1; P = 0.04) were associated with HIV infection in IVDU, and low education level (P = 0.02, test for trend), previous transfusion (OR, 9.1; P = 0.003), origin from sub-Saharan Africa (OR, 5.4; P = 0.05) and use of petroleum-based lubricants (OR, 15.2; P = 0.001) in non-IVDU. HIV prevalence remains relatively low among non-IVDU prostitutes in Europe. While intravenous drug use remains the most important risk factor for HIV, petroleum-based lubricants (used by 10% of women in this study) may be a risk factor for HIV among European female sex workers; over 80% of those interviewed always used condoms with clients.