This article is interested in the impact of a singular international phenomenon, namely the global securitisation of the HIV/AIDS epidemic, on the domestic structure of three Southern African states: Botswana, Mozambique and South Africa. These countries are geographically located in the epicenter of the global HIV/AIDS epidemic, Southern Africa. However, notwithstanding their common HIV/AIDS burden, Botswana, Mozambique and South Africa present quite different political cultures and institutions which reflected upon the distinctive way they responded to the influence of international HIV/AIDS actors and norms. So, by investigating the latter's impact in these rather diverse settings, the present analysis aims to empirically demonstrate and compare variations in the effects of norm adaptation across states. To carry out this evaluation, the study provides a framework for understanding the securitisation of HIV/AIDS as an international norm defined and promoted mainly by the Joint UN Programme on HIV/AIDS (UNAIDS), the US government and transnational HIV/AIDS advocacy networks. The HIV/AIDS securitisation norm (HASN) is an intellectual attempt of the present work to synthesise in a single analytical concept myriad of ideas and international prescriptions about HIV/AIDS interventions.