In 1988, 1233 prostitutes from different geographic areas of Kinshasa participated in a cross-sectional survey on HIV infection and other sexually transmitted diseases (STDs). Despite relatively good knowledge about AIDS and STDs, the reported preventive behaviour was poor. Only 12% of the women reported regular use of condoms, while >50% of the women reported regular use of antibiotics and 38% reported doing nothing specific to prevent STDs. Thirty-five per cent of the women were HIV-positive compared with 27% in a similar survey in Kinshasa in 1986. The prevalence of other STDs was very high, ranging from 5% for genital ulcer disease (GUD) to 23% for gonococcal infection. HIV-positive women were older than HIV-negative women (26.9 versus 25.4 years;P< 0.001), had a significantly lower level of reported condom use (9 versus 14%,P= 0.009), and reported more frequent use of antibiotics to prevent STDs (55 versus 42%,P= < 0.001). The prevalence of syphilis, gonorrhoea, chlamydial infection and trichomoniasis was not higher in HIV-positive women compared with HIV-negative women. However, HIV-positive women had a higher prevalence of GUD (9 versus 3%,P< 0.001), antibodies against Haemophilus ducreyi (82 versus 57%,P< 0.001), antibodies against herpes simplex virus type 2 (96 versus 76%, P < 0.001), condylomata accuminata (5 versus 1%,P= 0.003) and cytologic evidence of human papilloma virus on Papaniclaou cervical smear (11 versus 5%,P= 0.006). This study confirms the high incidence of HIV and other STDs among prostitutes in Africa. Taking into account the low frequency of effective preventive behaviour, these women are at high risk of acquiring and/or transmitting HIV. Targeted interventions aimed at increasing condom use and lowering STDs levels among this population are of the highest priority.