Labour Party candidate Alex White is the first person to be elected to the new Seanad as a result of a voting pact between his party and Sinn Féin, write Stephen Collinsand Michael O'Regan.
The Labour gain came at the expense of Fine Gael rather than Fianna Fáil, and indicates that the Government may not be under as much pressure to retain its majority in the Seanad as had been widely forecast.
The Labour-Sinn Féin alliance paid further dividends for the two parties when it emerged late last night that Sinn Féin's Pearse Doherty had topped the poll in the Agriculture panel, with Labour's Alan Kelly coming second.
The result of the election to the five-seat Cultural and Educational panel saw Fianna Fáil retaining three seats, Fine Gael retaining one seat and Labour gaining a seat.
The country's 1,082 county councillors, TDs and senators make up the electorate for the five vocational panels which are being filled this week.
The result of the vote for the Cultural and Educational panel showed that the Labour/Sinn Féin pact held up, and that both the Green Party and the Progressive Democrats delivered on their commitment to Fianna Fáil.
There was one change of personnel on the Fianna Fáil ticket, with defeated Dáil candidate from Donegal North East Cecilia Keaveney replacing long-serving colleague Paschal Mooney, who had been in the Seanad for 20 years.
The other two Fianna Fáil senators on this panel, Ann Ormonde and Labhrás Ó Murchú, retained their seats.
The Fine Gael seat was won by Liam Twomey, who lost his seat in Wexford in the general election. He was also the party's health spokesman in the last Dáil.
He edged out Terence Slowey of Donegal South West for the seat. By that stage of the count, Mr Slowey had pulled ahead of the outgoing Fine Gael senator, Fergal Browne from Carlow, who lost his seat.
While the strength of the Fianna Fáil vote and the Labour/Sinn Féin pact were important factors, the Fine Gael loss ultimately came about because the party's two strongest candidates were on the inside panel nominated by Oireachtas members.
Both Mr Twomey and Mr Slowey were ahead of Ms Ormonde on the last count but because of the special rules governing Seanad elections, under which a set number of seats are reserved for candidates of outside nominating bodies, the Fianna Fáil candidate was elected.
After topping the poll in the Cultural and Educational panel, the newly-elected Senator White said he was delighted and honoured to have been elected to the Seanad which he said performs "a very important function in our legislative process"
He defended the Labour-Sinn Fein voting pact as being as much "a mathematical proposition" as a political one. "It is an arrangement which has been made all over the country in local authorities."
He said he would "work tirelessly towards regaining a Dáil seat for the Labour Party in Dublin South." He narrowly failed to win election to the Dáil in the general election.
One of the surprising features of the count was that 10 of the 1,082 votes were deemed to be invalid. There was some surprise that 10 professional politicians failed to either fill in their ballot papers correctly or had allowed some mistake to be made in the validation paper that accompanied their ballots.
Counts for the two university constituencies will begin today.