This paper, based on a review of the literature of socio-behavioural research in this field, shows how the AIDS epidemic has renewed traditional approaches to patients behaviour toward medical treatment by substituting the notion of adherence for the traditional one of compliance. It shows how this issue of patients adherence has come to the forefront of HIV care with the recent diffusion of highly active antiretroviral therapeutics (HAART), because inadequate adherence has profound implications for the individual and public heath effectiveness of these therapeutic advances. The paper argues that two alternatives, and indeed conflicting, approaches to adherence to treatment in HIV infection however persist. The aim of the first approach remains to predict and correct non-adherent behaviour in certain patients and sometimes suggests that such predictions may provide justification for denying individuals treatment. This 'predictive' approach focuses on identification of individual barriers to 'good' adherence and calls on social science research to help improve the 'acceptability' of prescribed regimens for patients. An alternative 'empathic' approach focuses more on encouraging and supporting all HIV-infected patients medically eligible for HAART to devise appropriate individualised plans that can facilitate management of their treatment in their daily life. This latter approach more willingly learns from social science research which recognises the patient's subjective experience of illness as a central concern. In the future, the respective contributions of these two alternative approaches will have to be judged on the basis of their capacity to analyse both the factors which influence HIV-infected patients' initial adherence to antiretroviral treatment and those, potentially quite different, which interfere with adherence on the long term. They will also be judged for their capacity to inspire effective psychological and socio-behavioural interventions aimed at facilitating patients adherence.