Anticoagulated patients represent an important and increasing proportion of the patients with head trauma attending the ED, but there is no international consensus for their appropriate investigation and management. International guidelines vary and are largely based on a small number of studies, which provide poor-quality evidence for the management of patients taking warfarin. This article provides an overview of the clinical research evidence for CT scanning head-injured patients taking warfarin and a discussion of interpretation of risk and acceptable risk. We aim to provide shop floor clinicians with an understanding of the limitations of the evidence in this field and the limitations of applying ‘one-size-fits-all' guidelines to individual patients. There is good evidence for a more selective scanning approach to patients with head injuries taking warfarin than is currently recommended by most guidelines. Specifically, patients without any head injury-related symptoms and GCS score 15 have a reduced risk of adverse outcome and may not need to be scanned. We argue that there is evidence to support an individualised approach to decision to CT scan in mild head injuries on warfarin and that clinicians should feel able to discuss risks with patients and sometimes decide not to scan.