To determine the prevalence of HIV-1 and HTLV-I/II among female prostitutes from different areas of the city of Buenos Aires, we studied serum samples from 237 individuals (mean age: 25; range 17 to 39). Prostitutes were recruited from 16 different Buenos Aires locations with different economical status. Information on sexual behavior, health and socioeconomic conditions was collected through a questionnaire. HIV-1 and HTLV-I/II antibodies (ab) were tested by ELISA (Abbott) and Particle agglutination (Fujirebio, Tokyo) respectively. Positive results were confirmed by immunofluorescence assay. Samples that were positive for HIV-1 antibodies were also tested for p24 antigen (Abbott). VDRL for syphilis was performed in all samples. Fifteen (6.3%) out of the 237 individuals were positive for HIV-1 antibodies, Moreover, 2 (0.8%) HIV-1 seropositive prostitutes were also positive for HTLV-I/II antibodies and for HIV p24-Ag. Eventhough PCR for HTLV-I/II was not performed, titration by IFA in these two samples suggests HTLV-I. Our serologic results indicate a relatively high HIV-1 infection among prostitutes working in Buenos Aires. As we previously mentioned for other risk groups, we found an association between HTLV-I/II and HIV-1 infection in this particular group. Although we did not find any significant difference between HIV-1 seropositivity and the variables analyzed through the questionnaire, the prevalence of HIV-1 infection was higher in prostitutes working in mask brothels ('sauna or massage houses') as compared with hotel or street prostitutes.