Background: The aim of this study is to examine individual and contextual factors associated with high-risk sexual behaviour in sub-Saharan Africa. Heterosexual relationships represent the major route of HIV/AIDS infection in Africa. Thus, understanding sexual behaviour is an essential step toward any effort to reduce the spread of the HIV/AIDS epidemic.

Methods: We applied multilevel logistic regression analyses on Demographic and Health Survey (DHS) data for 262,727 respondents (level 1) nested with 10,914 communities (level 2) from 26 sub-Saharan countries (level 3).

Results: In all 26 countries studied, men were significantly more likely than women to have reported premarital sex. Except for Congo and Ethiopia, men were also significantly more likely to have reported non-spousal sex. At the community and country levels, there was statistically significant clustering of reported high-risk sexual behaviour. The following individual factors were associated with higher odds of reporting premarital and non-spousal sex: male gender, higher educational attainment and higher wealth status. The following contextual factors were associated with higher odds of reporting premarital and non-spousal sex: ethnic diversity, urban residence and small household size.

Conclusion: We found that community and societal measures of social disorganization are important predictors of high-risk sexual behaviour. Thus, interventions aimed at reducing highrisk sexual behaviour should be implemented not only at the level of the individual but also at the community and societal levels.