Figures from the Irish embassy in London suggest 2018 will be a record year for passport applications.
Nearly 45,000 people have applied for a passport in the first half of the year.
It is thought demand could reach 90,000 by the end of the year.
That would be an increase of around 10,000 on 2017.
Fine Gael Senator Neale Richmond says the rise in demand is Brexit-related.
"Those who are entitled to passports are either grandchildren or children of Irish citizens. They are staking their claim to there citizenship," said Mr Richmond.
"Given that we are on course for 90,000 applicants in 2018 and the year before the [Brexit] referendum we had about 45,000 - which is the consistent number - we've seen this increase double due to one major thing that happened in 2016.
"There might be smaller issues, but in the large, it has all been Brexit related and the fears that come with that."
- Digital Desk