The HSE is reminding people to get the MMR jab, and to know the signs of measles.
The warning follows confirmation two people in Dublin contracted the virus while in Europe earlier this month.
Dr Helena Murray, Specialist in Public Health Medicine said, "Measles can be a serious illness and is highly infectious.
"The best protection is to be fully vaccinated with two doses of MMR (Measles, Mumps, and Rubella) vaccine."
Health officials are concerned they may have come into contact with other people while highly contagious when they arrived home.
Anyone who suspects they may have the virus is being advised not to go to hospital, but to phone their GP.