Gardaí at Blanchardstown are investigating a suspected forged euro note.
The €10 note was found at a newsagents in Hartstown, West Dublin, today.
This is the third suspected forgery incident with the new currency in the Republic. This evening two euro notes that were sent by Co Cavan businesses to the Gardaí for examination on suspicion of being forgeries turned out to be genuine. They only appeared fake because they were wet, the Central Bank said.
The €5 and €10 notes were spent in a pub and drapery shop in Bailieboro yesterday. Gardaí earlier said these notes appeared to be high quality fakes.
Gardaí warned businesses and shoppers earlier today to be on their guard following the discovery of a poor-quality photocopy of a €10 note in Co Kildare.
A Garda spokesman described the note, spent at a supermarket in Straffan, in Co Kildare, as "a crude forgery".
The forged note was reportedly slightly smaller and did not have the security features of a genuine €10 note, such as the watermark or metal strip. The paper and texture of the note was described as poor.
All forged notes found in the State are taken to the Central Bank to be analysed. The results would be fed into a European database to assist countries in the battle against counterfeiting.
The only other fake notes to have been reported in the eurozone were found in Germany, a spokesman for Ireland's Central Bank said.
The chairman of the Euro Changeover Board of Ireland, Mr Philip Hamell, called for vigilance.
"There are only a few fake notes at the moment, I am glad to say, but forgeries are a concern," he said.
"The appearance of the notes are shown in the euro handbook. So many people now have true notes that they should take time to familiarise themselves with the appearance of euro notes and coins and keep an eye out for anybody trying to pass off a forgery."