President Mary McAleese and Taoiseach Enda Kenny have attended a ceremony in Dublin to honour all Irish people who died in past wars or on service with the United Nations.
Commemorations were also held around the country.
About 1,000 people attended the open-air ceremony in Dublin at the Royal Hospital Kilmainham.
Most of the Cabinet were present, including Eamon Gilmore, Ruairi Quinn, Brendan Howlin, Richard Bruton, Jimmy Deenihan, Alan Shatter, Frances Fitzgerald, Leo Varadkar and Joan Burton.
Members of the Council of State were led by Chief Justice John Murray, Ceann Comhairle Seán Barrett and Cathaoirleach of the Seanad Patrick Burke.
The Chief of Staff of the Defence Forces, Lt Gen Sean McCann, and Garda Commissioner Martin Callanan were present.
Senior diplomats also attended including British Ambassador Julian King. Hundreds of veterans from both the Defence Forces and the British Forces were present.
Among the hymns sung by soloist Regina Nathan were ‘I Vow to Thee My Country’ by Gustav Holst, ‘Pie Jesu’ by Gabriel Faure and ‘Oft in the Stilly Night’ by Thomas Moore.
The ceremony began with military pipers and band playing 'Limerick's Lament'. An inter-faith service followed with prayers being offered for those who died in the cause of the freedom society now enjoys.
Those leading the prayers included the Church of Ireland Archbishop of Dublin, Dr Michael Jackson, Monsignor Lorcan O'Brien (Roman Catholic), Rev Dr Robert Buick (Presbyterian), Rev Ian Henderson (Methodist), Imam Sheikh Hussein Halawa (Muslim), Rabbi Zalman Lent (Jewish), and Father Mikhail Nasonov (Russian Orthodox).
President McAleese laid a wreath, a minute's silence was observed and the ceremony ended with a flypast by the Air Corps.
Other cities stage events
The National Day of Commemoration has been marked with a ceremony at City Hall in Limerick.
Mayor of the City, Cllr Jim Long, laid a wreath in memory of the dead.
Prayers were said by representatives of the Catholic, Jewish, United Presbyterian and Methodist churches in Limerick, and from the Church of Ireland and the Islamic communities.
Veterans and their families, as well as a wide section of the community in Limerick, attended the ceremony.
There were prayers for those who had died and prayers for peace, and the attendees were asked not to forget the sacrifice of all those who served and fought for justice, freedom and for the dignity of the human race, and in particular for those who fell in the carnage of battlefields so far from home.
Members of the 12th Infantry Battalion from Sarsfield Barracks in Limerick rendered honours and raised the Tricolour after a minute’s silence.
Representatives of the Organisation of National Ex-Servicemen and Women and UN veterans welcomed the National Day of Commemoration being held in towns and cities outside Dublin.
They said it suited ex-servicemen and women, many whom were elderly, to be able to mark the day locally, without the difficulties and expense of having to travel to Dublin.
It is the first time national commemoration ceremonies have been held outside Dublin.
There were also events in Cork, Galway, Sligo, Kilkenny and Waterford.