They say a person traveled through the airport on May 19 while infectious with the highly contagious disease.
The person arrived on a Lufthansa flight at the Tom Bradley International Terminal and was at the airport for five hours before getting on a connecting flight out of Terminal 7.
Anyone who was known to be sitting near the traveler will be notified. But if you were in those terminals at that time you should monitor yourself for any symptoms.
Symptoms include high fever, cough, rash, runny nose and red watery eyes. They usually start appearing more than a week after initial exposure to the virus.
While childhood vaccination is common, the World Health Organization says more than 136,000 people died from measles in 2022 - most of them unvaccinated people or young children.