This article examines how pandemic influenza has been framed as a security issue, threatening the functioning of both state and society, and the policy responses to this framing. Pandemic influenza has long been recognised as a threat to human health. Despite this, for much of the twentieth century it was not recognised as a security threat. In the decade surrounding the new millennium, however, the disease was successfully securitised with profound implications for public policy. This article addresses the construction of pandemic influenza as a threat. Drawing on the work of the Copenhagen School, it examines how it was successfully securitised at the turn of the millennium and with what consequences for public policy. © 2012 Copyright Taylor and Francis Group, LLC.