More than 400 inmates have registered to vote in the forthcoming general election, it has emerged.
The prisoners will be the first group of inmates ever to vote in an election under a new scheme which re-enfranchises people serving prison sentences.
Until now, once a prisoner was in jail on the day of a ballot they were unable to vote.
However, under new procedures prisoners have been invited to join the electoral register in the areas where they lived before being imprisoned.
In the upcoming general election they will be able to cast their vote by post for candidates in their home constituencies.
The Government decided last year to allow prisoners to vote to comply with a ruling by the European Court of Human Rights.
The Government plan was drawn up in consultation with the Attorney General and the Department of Justice.
It was devised by Minister for the Environment Dick Roche, with primary legislation introduced last year providing for the changes.
Notices appeared in the national media after Christmas inviting prisoners who wanted to vote to register with their local authorities.
The deadline for registration was February 14th last.
The Department of the Environment, which has a co-ordinating role in all electoral registers, has said 404 of the 3,200 prison population had registered to vote by the deadline date.
A spokesman said this figure may increase closer to the general election, which is expected to take place in May.
He said prisoners wishing to register late could do so by having their names added to supplementary electoral registers. These are opened by all local authorities in the weeks before an election.
Under Irish law, a prisoner's right to vote had never actually been rescinded by the authorities.
In practice, however, the State has never provided prisoners with the ability to vote via a postal ballot.
The Government began a review of the issue in October 2005 when the European Court of Human Rights in Strasbourg ruled that the British government had violated a prisoner's rights by refusing him the opportunity to vote in an election.
The landmark ruling in the case of John Hirst, a British prisoner sentenced to life imprisonment for manslaughter, found that any departure from the principle of universal suffrage risked undermining the democratic validity of the legislature elected and its laws.
The ruling was not binding on the 46 countries that are signatories to the European Convention on Human Rights, but could have paved the way for similar actions by Irish prisoners.
Ireland is among 13 signatories to the convention.
The Hirst judgment by the European Court of Human Rights diverges from a previous ruling by the Supreme Court in the Republic, which found against a prisoner's right to vote in elections in July 2001.
In a unanimous judgment, the Irish five-judge court found that while prisoners were detained in accordance with law, some of their constitutional rights, including the right to exercise the franchise, were necessarily suspended.