Young people are ignoring the dangers of drink-driving, police have said as the first results of an all-Wales summer crackdown are released.
Officers from the four forces carried out almost 8,000 breath tests
Officers said it was "disappointing" a high number of drivers under 25 had provided a positive breath test in the five-week period between June and July.
In north Wales, 31 of the 86 who tested positive were aged between 17 and 25.
Some 400 drivers, of all ages, were over the legal limit when 7,970 tests were carried out by the Welsh forces.
That figure means 5% of all motorists breathalysed during this time were over the limit.
Results collected by the North Wales, Dyfed-Powys and South Wales forces showed 98 of the 295 drivers aged between 17 and 25 provided a positive breath test. No Gwent figure was available.
The number of people, of all ages, found to be over the limit was highest in Gwent where 105 of the 1,857 people stopped gave a positive breath test - 5.6% of the total.
South Wales was next with 5.1%, followed by North Wales at 4.9% and lastly Dyfed-Powys at 4.2%.
Elsewhere, Gwent Police stopped four people unfit to drive through the influence of drugs - only one other person under the influence of drugs was stopped by the other three forces.
And in cases where drivers were breathalysed by police following a collision, 33 of the 146 people in the Gwent force area were over the limit - the highest percentage among the four force areas.
Ch Supt Geraint Anwyl said: "It is disappointing that, despite the publicity given at the start of this campaign, a number of young drivers and others have chosen to drive while clearly over the limit."
The drink and drugs campaign continues until September
He said that police across Wales would continue to focus on drink drivers throughout the rest of the summer in order to make the roads safer for everyone.
And Ch Insp Phil Davies, of Dyfed-Powys Police, added that education and enforcement would be used to target the issues of drinking or taking drugs and driving.
He said: "Drink/drug driving will not be tolerated and we will continue to drive home this message to those within our driving population that would consider otherwise."
More drivers than ever were tested as part of this year's campaign, including 1,113 more in the five weeks than during the entire All Wales campaign of 2006.
The initiative runs until the beginning of September.