We describe the findings from a research ethics case study, linked with a team evaluating a package of intervention services to prevent HIV infection in adolescent girls and young women (AGYW) living in a rural and poor setting of KwaZulu-Natal, South Africa.We conducted qualitative interviews (n=77) with members of the linked research team evaluating the intervention programme, programme implementing staff, AGYW enrolled in the intervention programme, caregivers, ethics committee members, Public Engagement officers, community advisory board members and community stakeholders. Data were analysed iteratively using thematic framework analysis. Themes were determined by the study aims combined with an inductive development of codes emerging from the data.The findings show that the burden of providing ancillary care fell primarily on the shoulders of frontline researchers and programme staff. Dilemmas around responding to gender-based violence illustrated the limits of ‘referral to services’ as a solution for meeting ancillary care obligations in contexts with barriers to basic health and social services.Our findings show important gaps in meeting ancillary care needs. Participants’ needs required social and economic support which frontline researchers and implementing partners were not able to meet, causing moral distress.