Using an unlinked anonymous survey the seroprevalence of HIV, HTLV-I and HTLV-II was analysed among female sex workers. They were surveyed when they attended sexually transmitted disease clinics in six Spanish cities during the period 2000-2001. Fifty-eight percent of the 3149 women analysed came from Latin America or sub-Saharan Africa. The total prevalence of HIV was 0.7%, rising to 15.9% amongst injecting drug users (IDUs). When this group was not included, the prevalence amongst the Latin-Americans or sub-Saharan Africans was 0.8% and amongst the women from other origins 0.3% (p = 0.148). 33.3% of the women infected with HIV already knew about their infection. The prevalences of HTLV-I and HTLV-II were 0.3% and 0.2%, respectively. The prevalences of these three infections in this collective were low if evaluated without the IDUs.