There were 307 deaths and almost 1,200 people were seriously injured on the roads of Co Donegal between 1996 and 2009.
The statistics were published in a report compiled by the Road Safety Authority and An Garda Síochána.
The findings were revealed at the launch of a new initiative in which the RSA and gardaí will focus on individual counties to assist local agencies strengthen road safety in their communities.
Donegal was chosen as the first county to visit because of its record of fatalities.
RSA Chief Executive Noel Brett described Donegal's record as 'appalling', but he said things have improved and the number of deaths has been reduced.
This time last year, eight people had died on Donegal's roads, but to date this year three people have lost their lives.
Speed was a factor in two out of every five fatalities in Donegal during the period studied and almost 28% of those killed were young men aged 17 to 24.
Assistant Garda Commissioner Kieran Kenny said 'Operation Face' had made a big difference by targeting specific drivers and the detection of a range of offences had increased significantly, including an increase of 82% in the detection of speeding offences.
Mr Brett said the Donegal Road Safety Working Group is one of the most active in the country and he hoped that other counties would learn from its experience.
The statistics show that Co Donegal accounted for 6% of fatalities in Ireland during the period examined, despite making up only 3.5% of the population.