OBJECTIVES: To investigate whether the indicators of sexual risk behaviour, defined by UNAIDS for use among members of general populations, have been found as risk factors, to examine how information on sexual behaviour is collected and summarised in order to calculate the indicators, and to look for possible sources of error in the data and in interpretation of those indicators. METHODS: The literature on risk factors for HIV infection was reviewed. Indicators were calculated for countries where data were available for two or more points in time. RESULTS: Indicators of sexual behaviour describe behaviours that are relevant to HIV risk and that are amenable to change. These behaviours do not correspond closely to the individual risk factors for HIV infection that have been identified in observational studies. CONCLUSIONS: Although potential errors of both measurement and interpretation exist, most of the indicators currently defined can fulfil their purpose, providing they are used with caution. Many of the indicators should not be interpreted in isolation but need supporting information to make sense of trends or differences between groups. Much of this information is provided by other indicators. The source of the data used to calculate the indicator is potentially important and should always be provided with indicator estimates. Some estimate of the accuracy of the estimate, either by means of confidence intervals or the number of respondents, should be given.