An assessment of EU states showed that Irish authorities, motorists and other road users have helped cut deaths from 411 in 2001 to 212 last year.
The European Transport Safety Council (ETSC) ranked Ireland a record high of sixth — up one place from the 2010 rating.
Noel Brett, Road Safety Authority (RSA) chief executive, praised road users but warned them against complacency.
“Yet again road users in Ireland have shown that by taking road safety intothe heart of their communities, many lives can be saved and injuries prevented,” he said.
“Your achievement is remarkable and you have become an example to the rest of Europe and indeed the world by your responsible actions on the roads.
“But these achievements can be easily taken away from us if we allow ourselves to become complacent. There is still a big gap between Ireland and the safest countries in Europe.”
The ETSC report found 10 other countries achieved or improved on Ireland’s 48% reduction in road deaths since 2001.
Latvia, Estonia, Lithuania, Spain, Luxembourg, Sweden, France and Slovenia all reached the European Commission target of a 50% reduction in road deaths by 2010.
Although Ireland fell just short of this, the cut in the road death rate was above the EU average of 43%.
Mr Brett had this message for road users: “I would ask you all to keep up the great work and to renew your efforts to stay safe on the roads. Already this year, your efforts are showing results with 16 fewer deaths on our roads to date compared with the same period last year.”
The five countries with better track records than Ireland remain Sweden — just 28 deaths per million — Britain, Malta, the Netherlands and Germany, but roads here are now safer than in Australia — 61 deaths per million — and the USA (107 deaths per million).
EU officials said more than 100,000 lives have been saved on the roads since 2001 with the financial benefit estimated to be €176 billion.
Richard Allsop, of the ETSC and chairman of the PIN Programme to mark road safety, said: “These figures show the immense value to society of working to make using the roads safer.”
Mr Brett said: “The ETSC report highlights Ireland’s efforts to improve safety on rural roads, the safety of vulnerable road users, such as pedestrians,cyclists and motorcyclists, and reduce serious injuries.”