Aim/Background: Focused Assessment with Sonography for Trauma (FAST) has evolved into a common point-ofcare diagnostic investigation in UK Emergency Departments (ED). Its role in the management of blunt abdominal trauma is well recognised. The aim of this study was to determine if the FAST scan can play a role in the management of non-traumatic patients. Method: A literature review was performed with the emphasis on the use of FAST scanning in the non-trauma setting. Results: In the acutely ill, undifferentiated, septic or decompensated patient, a Focused Assessment for Free Fluid (FAFF) scan may be of benefit, as a goal-directed investigation, to search for free fluid as an indicator of underlying disease source. The presence of free fluid in the non traumatised peritoneum implies primary or secondary intraabdominal pathology requiring urgent specialist review and management. A FAFF scan can also play a role in the management of patients with abdominal aortic aneurysm, ectopic pregnancy and some thoracic conditions. Conclusion: There is mounting evidence to support the efficacy of using such focused ultrasound, with its 'rule-in' high specificity, for helping reduce the potential differential diagnoses, at an early stage, in critically ill patients. We advocate the use of the term FAFF and not FAST, when emergency ultrasound is applied to non-traumatic clinical cases. We advise its liberal use by accredited clinicians, as part of a structured approach to the assessment of the undifferentiated, unwell patient presenting to emergency departments - especially those in shock or critically ill.