This paper examines the demographic profile of two cohorts of sero-discordant couples enrolled in research activities at two clinical research sites in Kigali, Rwanda and Lusaka, Zambia and compares their background characteristics by country, gender and sero-status. Differences between the two cohorts represent economic and cultural differences between the two countries. Recruitment procedures appear to be successful in reaching the intended audience - couples from poor urban communities - and we suggest that similar recruitment strategies could be adopted to reach other population groups in other settings. The profiles of sero-discordant couples highlight several potential intervention points, and call for attention to be focused towards prevention efforts aimed at young women and their male partners.