BACKGROUND: Non-traumatic undifferentiated hypotension is a common critical presentation in the emergency department. In this group of patients, early diagnosis and goal-directed therapy is essential for an optimal outcome. The usefulness of focused bedside ultrasound is reviewed and a protocol for Abdominal and Cardiac Evaluation with Sonography in Shock (ACES) is proposed. METHODS: The protocol consists of six windows including cardiac, peritoneal, pleural, inferior vena cava and aortic views, and aims to shorten the time period taken to establish a diagnosis and hence to deliver the most appropriate goal-directed therapy. Its use in seven case examples is described. RESULTS: In all cases the ACES protocol helped in guiding the initial management while further information was obtained. CONCLUSION: The six-view ACES protocol is a useful adjunct to clinical examination in patients with undifferentiated hypotension in the emergency department. A prospective randomised trial or multicentre database/registry is needed to investigate the validity and impact of this protocol on the early diagnosis and management of hypotensive patients.