To estimate the prevalence of HIV-1, HIV-2 and HTLV-I among female prostitutes, and to identify possible risk factors for HIV transmission in this collective, sera and epidemiological information from 71 prostitutes were obtained. Using the local network of a well-defined area in southern Catalonia, all prostitution bars were identified and their working women interviewed using a previously validated questionnaire. Eight sera were found positive for HIV-1 antibodies. Of those, 7 sera were also positive in the HIV-2 assay, probably as a result of cross-reactivity between the two viruses. All sera were negative for HTLV-I antibodies. In our area, where intravenous drug users (IVDUs) account for the majority of AIDS cases, the use of drugs by the prostitutes or by their steady sexual partners seems to be the most important risk factor for HIV infection in that group.