The Centers for Disease Control and Prevention (CDC) issued this HAN Health Advisory to notify clinicians and public health officials about a confirmed measles case at a large gathering. On February 24, 2023, the Kentucky Department for Public Health (KDPH) identified a confirmed case of measles in an unvaccinated individual with a history of recent international travel. While infectious, the individual attended a large religious gathering on February 17–18, 2023, at Asbury University in Wilmore, Kentucky. An estimated 20,000 people attended the gathering from Kentucky, other U.S. states, and other countries during February 17–18, and an undetermined number of these people may have been exposed. This Health Advisory also highlights other recent large global measles outbreaks and associated U.S. importations, and the importance of early recognition, diagnosis, and appropriate treatment. CDC recommends that clinicians be on alert for cases of measles that meet the case definition.