Masturbation is a neglected topic in debates around biopower and biopolitics. This article takes Michel Foucault’s recasting of the idea of a regulatory, population-level form of biopower in terms of ‘mechanisms of security’ as its starting point for an investigation into the ways in which bodies enter into and are reshaped by biopolitical discourses on masturbation. While the notion of security faded from view in favour of Foucault’s better known focus on governmentality, this article argues that there is value in recovering the concept of security in the context of a genealogy of modern bodies. Specifically, it explores the possibility that a biopolitical perspective on security operates not only above, but also below the disciplining of individual masturbating bodies. The article proceeds, initially, via an examination of contemporary studies of masturbation, arguing that they largely neglect the material dynamism of bodies. The main focus, however, is on rereading some of the key works in the historical anti-masturbation literature from a complexity perspective. It is shown that these texts engage with a ‘population’ of vital forces and affects that must be regulated if life is to remain secure, and which circulate below the level of individual bodies in relation to a complex milieu. Finally, the article claims that men’s bodies appear as crucial sites of biopolitics, and that normative forms of masculinity can be regarded as interventions into embodiment that are designed to nullify or regulate complexity.