This paper examines the history of population screening through an analysis of contemporary medical journals. The term was first used in the modern sense in the inter-war years to describe the school health examination which sought to identify the early signs of disease and abnormality, a strategy which was extended to new recruits during the Second World War. After the war, screening began to target those illnesses in the civilian population which had a clear temporal trajectory, especially 'chronic' illnesses. Since the 1980s, enthusiasm for population screening has declined within the medical community: opportunistic screening has seemed more appropriate for diseases with multifactorial aetiology, and those programmes which have survived have been increasingly challenged through an expanding analysis of their potential harms. In identifying the early precursors of clinical disease in apparently normal populations, however, screening heralded the emergence of a new form of clinical practice concerned with the surveillance of 'healthy' patients within the context of new temporal spaces of illness.Keywords: screening, history, time A century or so ago 'screening the patient' would probably have referred to the use of curtains around the patient's hospital bed to provide privacy for a medical procedure. In the 1950s, it marked the brave new world of testing the population for the early stages of disease. Nowadays, it is likely to be a site of contestation over whether it confers benefits or harms. This paper attempts to map these changing uses of the term and the debates which have surrounded its deployment, from its first appearance in the inter-war years of the 20th century, through its period of ascendancy in the post-war years, to its more turbulent history in the early 21st century. In doing so the paper identifies underlying changes in the temporal dimension of illness, of which screening is simply one manifestation.The role of population screening within healthcare has been of interest to doctors, patients, lay groups, lobbyists, and other healthcare professionals, among others, but the analysis in this paper is based primarily on debates within medicine -the relationship with these other discourses is briefly discussed in the final section. Medical engagement with screening was accessed by examining contemporary medical journal articles, editorials and correspondence. Major medical journals are now digitalised and word searchable from their first issues, so they were used to identify when, and in what context, the notion of medical screening was separated from earlier different uses of the term. The subsequent expansion of the use of screening as a routine medical procedure was tracked through a range of medical journals published in both the UK and US supplemented by PubMed searches. Trends were charted in Excel (examples are available in the supplementary files accompanying this paper) and