Acute aortic dissection in the emergency department (ED) remains one of the riskiest clinical and medicolegal challenges facing ED physicians. The variability in clinical presentations and mimics, the unreliability of clinical assessments and initial screening tools, and the need for advanced imaging all present obstacles in making an accurate and timely diagnosis for this entity. This article reviews available information and evidence regarding pathophysiology, risk factors, clinical variations in presentation, the usefulness of different diagnostic testing modalities, and management options in the ED when considering this diagnosis. Key recommendations from recent guidelines are reviewed in the context of ED practice.