The Road Safety Authority said it was too early to say if the fall in traffic deaths in August was due to the introduction of mandatory alcohol testing in July.
Brian Farrell, RSA spokesman, said the 17 people killed so far this month was the lowest number of road deaths this month since 1999. Last year 24 people were killed in crashes in August, and the year before that it was 35.
"There has obviously been a change in behaviour, but it is too early to say if it is as a result of mandatory alcohol testing and whether it will be sustained.
"We would however, like to applaud motorists and encourage them to keep up this level of compliance, not just for August but in September and November too."
Since mandatory alcohol testing was introduced, the number of people caught drinking and driving has risen significantly. In the first eight months of the year 10,653 drivers were caught, an increase of 22 per cent on the same period last year.
Shane McEntee, Fine Gael road safety spokesman, welcomed the fall in road deaths, but he said the Garda Traffic Corps must be brought up to full strength as soon as possible to prevent fatalities rising again.