670 women (18-45 years old) were interrogated and bleed between december 1986 and december 1987, they worked in nightclubs with three different socioeconomical statuses: high (550); middle (50) and low (70). Serum samples were tested by an enzyme-linked immunosorbent assay (ELISA) and by an indirect immunofluorescent assay (IFA) as a confirmatory test. Three prostitutes (0,44%) were seropositive by ELISA and IFA test to HIV antibodies, who were working in a high socioeconomical nightclub; two of them had had blood transfusions and they had generalized lymphadenopathy; the third one did not have history of other high risk factors for AIDS. We found that mean duration of prostitution was 29 months and the mean number of sexual partners was 40 per month. All women were engaged in vaginal intercourse, using condom in 70% of occasions; 34% had oral sexual intercourse and 9% was engaged in regular anal intercourse. No significant correlations were found with the kind of sexual activity, use of condoms, intravenous injections, drug addiction, and other sexually transmitted diseases.