All passengers travelling to the United States from today will have their index fingers scanned and a digital photograph taken before departing Dublin or Shannon airport.
A machine-readable passport will also become a requirement from Tuesday, October 26th.
Holders of handwritten passports will need to apply for a visa, even if they would otherwise be eligible for travel under the Visa Waiver program.
Ireland is one of 27 countries currently participating in this program, which allows citizens of these countries to enter the United States for 90 days without a visa.
Children, including infants, who are named on a parent's passport must also have an individual machine readable passport.
The US Ambassador to Ireland, Mr James Kenny, said these combined measures offer greater security to travellers and make it harder for terrorists and criminals to use forged or stolen passports.