Leitrim, Laois, Kildare, Monaghan and Clare showed the biggest reduction in road deaths in the five years that saw Ireland set new safety records.
Noel Brett, RSA chief executive, said the success was down to everyone's individual efforts. "The reduction in road deaths in nearly every county in Ireland shows just what can be achieved when communities come together and say, 'enough is enough, we don't want any more people dying on our roads'," he said.
"All it takes to make a difference is for one person to say, 'I'm going to change my behaviour on the roads so that I can keep myself and others safe when we're out on the roads'."
The top 10 best-performing counties were Laois and Leitrim with a 100% improvement; Kildare at 95%; Monaghan 83%; Clare 79% and Tipperary, Carlow, Wicklow, Dublin and Donegal, who all achieved reductions of more than 70%.
The figures for fatalities in Offaly remained static during the five years and in Cavan road deaths increased by 20%.
Mr Brett urged people to continue to push for better safety levels. "If we all redouble our efforts in 2013, there is no reason why we can't make Ireland's roads the safest in the world," he said.
The RSA report showed 162 people died on Irish roads in 2012, 24 fewer than the previous year when 186 people died, and 51 fewer than 2010.
Between 2007 and 2012, the average reduction in road deaths was 57% when compared with the number of fatalities between 2004 and 2006, the RSA said.
The RSA said the total number of serious injuries sustained in crashes last year was not yet available but noted a 51% reduction in these injuries up to the end of 2011.