Over a third of emergency department patients are discharged with a symptom-based diagnosis (e.g. chest pain) after dangerous causes of their symptoms have been "ruled out." This diagnostic uncertainty causes patient distress and often leads to ED recidivism as patients seek a diagnosis. We will discuss the development and testing of a patient-centered approach to communicating about diagnostic uncertainty in the acute care setting. Danielle McCarthy, MD, MS Associate Professor & Vice Chair of Research, Department of Emergency Medicine Northwestern University Feinberg School of Medicine This seminar is co-sponsored by the Medical Faculty Council (MFC) at Northwestern University.