OBJECTIVES: To estimate rates of condom use in four urban populations in sub-Saharan Africa and to assess their association with levels of HIV infection and other sexually transmitted diseases (STDs). METHODS: Data were obtained from a multicentre study of factors that determine the differences in rate of spread of HIV in four African cities. Consenting participants were interviewed on sexual behaviour, and also provided blood and urine samples for testing for HIV infection and other STDs. Data on sexual behaviour included information on condom use during all reported spousal and non-spousal partnerships in the past 12 months. RESULTS: A total of 2116 adults aged 15-49 years were interviewed in Cotonou (Benin), 2089 in Yaoundé (Cameroon), 1889 in Kisumu (Kenya) and 1730 in Ndola (Zambia). Prevalence rates of HIV infection were 3.4% in Cotonou, 5.9% in Yaoundé, 25.9% in Kisumu and 28.4% in Ndola. Reported condom use was low, with the proportions of men and women who reported frequent condom use with all non-spousal partners being 21-25%, for men and 11-24% for women. A higher level of condom use by city was not associated with lower aggregate level of HIV infection. The proportions of men reporting genital pain or discharge during the past 12 months were significantly lower among those reporting frequent condom use in all sites except Yaoundé: in Cotonou, adjusted odds ratio (OR) = 0.28, 95% confidence interval (CI) = 0.09-0.94; in Kisumu, adjusted OR = 0.34, 95% CI = 0.14-0.83; and in Ndola, adjusted OR = 0.33, 95% CI = 0.12-0.90. The same association was found for reported genital ulcers in two sites only: in Cotonou, adjusted OR = 0.14, 95% CI = 0.02-1.02; and in Kisumu, adjusted OR = 0.18, 95% CI = 0.04-0.75. There were few statistically significant associations between condom use and biological indicators of HIV infection or other STDs in any of the cities. CONCLUSION: Similar levels of condom use were found in all four populations, and aggregate levels of condom use by city could not discriminate between cities with high and low level of HIV infection. It seems that rates of condom use may not have been high enough to have a strong impact on HIV/STD levels in the four cities. At an individual level, only a male history of reported STD symptoms was found to be consistently associated with lower rates of reported condom use.