Abstract The human immunodeficiency virus (HIV) originated from cross-species transmission of the simian immunodeficiency virus from primates to humans. Yet a significant minority of people in the United States (US) and South Africa believe that HIV was deliberately created by scientists as a bioweapon. Scholars in the humanities emphasise the historical context, socially situated character and psycho-social dimensions of such aetiological narratives. This is important, but so is the role of individual agents participating in the cultic milieu in which oppositional ideas such as HIV conspiracy theories are borrowed across national, ideological and political divides. This article discusses the origins of the legend of ‘HIV as bioweapon’ and summarises the available evidence on the prevalence of acquired immune deficiency syndrome (AIDS) conspiracy beliefs in the US and South Africa. This is followed by a discussion of the history of biowarfare and racial oppression which renders the legend (and its local South African variants) believable for many people. The article then moves beyond socio-historical analysis to argue that analytical space needs to be created to critique the political leaders who promoted AIDS conspiracy beliefs.