Iarnród Éireann recorded an all-time passenger high in 2006,with more than 43 million journeys made on its rail system.
The figures include Dart, Intercity and commuter services across the country, and represent a 14 per cent increase over the previous record of 37.7 million journeys in 2005.
The latest surge in growth has been attributed to strong customer response to service improvements, including an increase in Intercity and commuter services, and the Dart upgrade.
"This record growth, which will ensure we remain the EU's fastest-growing railway, is set to continue over the coming years, as we deliver on the full scale of development of our network and services outlined under Transport 21," a spokesman for the company said.
"In this task, we will ensure that we also continue our record in Iarnród Éireann of having the strongest performance amongst recipients of capital funding for infrastructure in delivering on time and on or under budget."