Out of 867 sex workers examined during 1998-2000 from the five important red light areas of Kolkata, 26.18%(227) were suffering from active syphilitic infection having positive VDRL test with titre 1/8 and above. Vaginal smear for gram staining was collected from all sex workers, and found positive for active gonorrhoeal infection in 41.8% (362). Culture positivity for gonorrheal infection was 34.14% (296). Sex workers were also having other STD infection, 23.64% (205) Trichomonas infection, 13.26% (115) Candidiasis, 8.77% (76), Gardenella and 3.0% (26) Chanchroid for which vaginal samples were found positive. HIV sero-positivity was found to be 13.2% (115) out of 867 blood samples examined from all sex workers under study. There were 0.34% (3) sex workers who were also positive for HIV II infection along with HIV-I infection. A case of HIV II alone was not detected in any of the sex workers. Around 49.6% (430) knew that STD/HIV can be prevented by use of condom. However, condom was used by only 6.57% (57) sex workers.