A review conducted for UNAIDS assessed the condom paradox — persistently high HIV and sexually transmitted infection (STI) rates among sex workers in Southern Africa who report using condoms — based on analyses of condom use and HIV and STI data, including qualitative country research. This review attempts to identify gaps and weaknesses in existing programmes and monitoring systems with comparative reference to ‘gold-standard’ examples from outside the region. Recommendations are provided for strengthening the programmatic response regarding HIV prevention with sex workers.