Abstract: Internet technologies are increasingly advocated as a means for transforming health care and improving people’s health. In the field of e-health questions on the health implications of internet use are typically approached through attempts at measuring the effect of internet use on health outcomes. In this, information is usually conceptualised as a form of knowledge/power and online information practices are enrolled in discourses on patient empowerment. Taking the different meanings ascribed to information in these approaches as my point of departure, in this thesis I rethink the implications of internet use on health through an empirical exploration of alternative conceptualisations of the relationship between information and health in the context of contemporary HIV treatment and care. I do this through two analytical moves. First, drawing on the concept of performativity, a concern with what effect internet use has on health is turned into one of how internet use enacts health. Second, rather than treating information as knowledge/power, through an analysis of how a specific group of women ‘living with HIV’ in the UK use the internet, I reconfigure the connections between internet use and health through a conceptualisation of information as care. Drawing on a range of empirical materials – including forty-seven in-depth interviews with patients and internet content providers, non-participant observations, document and website analysis – three areas of health-related internet use are analysed in detail: the seeking out of health-related and specifically biomedical information; the seeking out and sharing of experiential knowledge and narratives about living with HIV; meeting prospective partners and dating. However, rather than studying these areas of internet use in order to interrogate what they can tell us about the internet, I analyse them as part of the ethical regime of ‘living with HIV’, in which the virus, previously thought of as ‘terminal’, becomes, through info and bio technologies, normalised as ‘chronic’. From this perspective, enacting health not only entails working on and with one’s body, but also always invokes its distribution across bodies, to other areas and relations, including internet technologies and the networks of relations established via these technologies.