In an attempt to promote patient agency and foster more egalitarian relationships between patients and doctors, discourse concerning health and wellbeing in the UK has increasingly centred around the notion of informed and 'expert' patients who are able to effectively input into the direction and management of their own health care and treatment. While the relationship between a patient and their doctor can play a vital role in influencing the treatment decisions and health-related outcomes of people living with long term illness, little is known about the ways in which people living with HIV actually perceive their relationship with their doctors, nor the implications this may have for the types of treatment they may seek to use and the related information that they share. Drawing on 11 focus group discussions and 20 repeat interviews undertaken in 2008-2009 with HIV-positive adult migrants from Zambia, Zimbabwe and South Africa living in the UK, this paper argues that patient-doctor relationships can be heavily influenced by the perceived legitimacy of different forms of medical knowledge and treatments and by culturally influenced ideas regarding health, wellbeing and agency. Despite a desire amongst some migrants to use 'traditional' medicines from southern Africa as well as other non-biomedical treatments and therapies, the research found that the perceived lack of legitimacy associated with these treatments in the UK rendered their use a largely clandestine activity. At the same time, many patients made clear distinctions concerning issues affecting their immediate health and factors influencing their more general wellbeing, which in turn, impacted upon the information that they chose to share with, or conceal from, their doctors. Such findings challenge assumptions underpinning policy promoting patient agency and have significant and, in cases, potentially adverse implications for the safety and effective administration and management of HIV treatments in African migrant populations and possibly more generally.