Objectives: To review the sexual behaviour data collected in the Demographic and Health Surveys (DHS) and other similar national surveys from the perspective of data quality.

Methods: Two indicators of premarital and higher risk sexual behaviour were analysed for 31 surveys in 10 countries in sub-Saharan Africa and Latin America and the Caribbean. The analysis focused on the internal consistency of trends and gender differences in the reported indicators.

Results: The authors found fluctuating trends in premarital sex in sub-Saharan Africa but consistent increases in Latin America and the Caribbean. Changes in questionnaire design do not seem to contribute to these trends and there is evidence that the increase in premarital sex is genuine in Latin America. Trends in sex with non-spousal, non-cohabiting partners show large fluctuations and inconsistencies between surveys in some countries but not others. Men are consistently more likely to report non-marital sexual partners than women and unmarried women are less likely than unmarried men to report casual partners.

Conclusions: Surveys are potentially a valuable source of information on sexual behaviour but there are sufficient grounds for concern to warrant considerable caution in the use of survey data to monitor trends in sexual behaviour. Survey findings must be evaluated carefully and interpreted in the context of other available information. These results caution against placing heavy emphasis on short term changes in sexual behaviour between individual surveys and highlight the need for attention to quality in data collection.