Objectives: To describe the sexual and reproductive behaviour of adolescents in sub-Saharan Africa, particularly 15- to 19-year-olds. Methods: Using DHS/AIS data (2000–2010), nine indicators of adolescent behaviour and one of adult attitudes towards condom education for adolescents were described for 24 countries. Indicators were disaggregated by gender, urban/rural residency and educational status, and time trends were described. Results: Up to 25% of 15- to 19-year-olds reported sex before age 15; this proportion shrank over time in many countries. In most countries, ≥5% of females reported marriage before age 15, and >20% had commenced childbearing. Early sexual debut and childbearing were more common among the least educated and/or rural females. Reporting of multiple sexual partnerships was more common among males than among females, but decreases over time were more common among males. Urban males and females, and females with higher education, were more likely to report multiple partnerships. Urban youth and those with higher education also reported more condom use. Adult support for condom education for 12- to 14-year-olds has increased over time to 60–65%. Conclusions: Many 15- to 19-year-olds are at risk of HIV/STIs and unplanned pregnancies because of multiple partnerships and insufficient condom and other contraceptive use. In many countries, trends are moving in a favourable direction. To better inform prevention programmes in this important area, we recommend routine collection of sexual and reproductive behaviour data for adolescents aged <15 years, expanding the data collected for 15- to 19-year-olds to include detailed information on sexual behaviour within partnerships, and disaggregating data according to sociodemographic variables.