Stigma is not a new concept; however, it remains highly significant in the context of HIV/AIDS in South Africa. There is wide consensus that HIV/AIDS-related stigma compromises the well-being of people living with the disease. This paper is part of a larger study that seeks to understand the social and cultural complexity related to the provision and outcomes of antiretroviral therapy (ART) in South Africa. It explores and analyses how patients on ART perceived and experienced stigma and how it has shaped their behaviour towards, as well as their understanding of the epidemic. The data have been collected by means of in-depth face-to-face interviews, conducted between June and November 2007, with a sample of 44 patients in an HIV/AIDS clinic in a resource-limited setting in Johannesburg, South Africa. The findings reveal that the level of felt and anticipated stigma is intense and affects all dimensions of living with HIV/AIDS, particularly disclosure and treatment. Stigma permeates the experience of HIV-positive people on ART who participated in this study. The intensity of HIV/AIDS-related stigma can threaten to compromise the value of ART, thus impacting on the daily lives of people living with HIV/AIDS (PLWHA). This study suggests that three decades into the epidemic, stigmatisation remains a core feature of the patient experience of HIV/AIDS. In the clinic in which this research was conducted, HIV/AIDS was regarded as a chronic condition increasingly manageable by ongoing access to ART. However, this approach was not shared by many family members, neighbours and employers who held highly stigmatised views.