Providing assistance to mobile populations has long been a challenge for healthcare providers and humanitarian organisations. The challenge is even greater when these populations need long-term chronic care for diseases such as tuberculosis or HIV, which require adherence to treatment and regular follow-up. This article examines the implications of medical care in contexts of displacement, when human movement is a major obstacle to ensuring compliance with treatment regimes. It argues that patients’ mobility can be integrated into health service provision through cross-border and regional referral systems, and examines how aid agencies can successfully work with other stakeholders, considering the impact of immigration policies, discrimination in health facilities, and xenophobia on the health of migrants in need of chronic care. It asks what the correct balance is to take in dealing with a medical crisis in a highly politicised environment. The experiences of MSF res in Southern Africa are explained as an illustration of this dilemma.