The original words and music for the National Anthem - Amhrán na bhFiann - handwritten by Peadar Kearney, have been sold at auction for ¤760,000.
It was purchased by an anonymous telephone bidder. However, the auction house believes it will stay in the country.
The item had been expected to fetch over ¤1m.
The Director of the National Museum earlier said the leaders of the 1916 Rising would not have wanted memorabilia to be sold at auction.
Dr Pat Wallace also said the State should not have to pay unreasonable amounts of money for historical items.
He was speaking ahead of today's auction in Dublin of more than 500 items from the 1916 Rising and War of Independence.
Earlier, two Ógra Sinn Féin members were arrested following a disturbance at the auction.
There were minor scuffles during protests at the sale of items which they said should be held by the Irish Government.
Today's auction by James Adam & Sons and Mealy's Auctioneers was held at St Stephen's Green.
It included other significant historical pieces including an original of the Proclamation of Independence dating to the Easter Rising in 1916.
The sale was hosted to coincide with the 90th anniversary of the Rising.
- Nine News: Sinéad Crowley reports on that and other items sold at an independent auction in Dublin today
- News At One: Dr Pat Wallace, Director of the National Museum, explains the type of items that would interest the National Museum
- News At One: Sandra Hurley reports on the auction of historical artefacts from the 1916 Rising
