Almost 200,000 people in Northern Ireland will miss out on the chance to vote in the European elections next month unless they get on the electoral register within a fortnight.
The Electoral Commission said today that with less than a moth to go before polling, up to 15% of eligible voters have still not added their details to the electoral register.
Those between 18 and 24 and people who have moved house recently account for the majority of those missing from the list.
Electoral Commission head Seamus Magee said: "In Northern Ireland eligible voters can make their voices heard by selecting their European Parliamentary candidates on Thursday, June 4.
"However not everyone is in a position to vote and many may wrongly assume that they are already on the register."
He added: "I am making an urgent appeal; to the thousands of people in Northern Ireland who have not yet registered to vote to do so by Tuesday May 19.
"Don't lose your vote and your voice at the June elections. Take a few minutes now to make your opinion count."
Applications forms can be found on the commission's website - www.aboutmyvote.com or obtained by calling the commission on 0800 03237000.
The commission also reminded those needing an Electoral Identity Card to vote to apply by May 22.