Angus schools have lost almost 168,000 days of teaching in the past three years due to unauthorised absences.
The shock figures have increased every year since 2015-16, with Forfar Academy the biggest offender.
The secondary saw 27,009 days lost to unauthorised absence, which includes truancy and family holidays for which permission was not granted.
A Courier investigation revealed that Montrose Academy (14,236), Arbroath Academy (13,840) and Arbroath High School (13,051) followed just behind in the table of 61 primary and secondaries.
Parents must get permission to take a child on holiday during term time and it is up to the head teacher how many days they can have off if leave is granted.
Former Montrose Academy deputy head and Craigie High School head teacher David May said: “I have no doubt that these pupils will leave school with poorer results than they could have done if they had not been missing lessons and this affects their future job prospects.
“Furthermore, parents and homes condoning absence from school is hardly a good example for their youngsters and their school reports will show this which colleges, universities and future employers take account of.
“Schools and councils are using all resources at their disposal, within the law, to reduce pupil unauthorised absences including the use of modern technology to alert parents and homes when pupils are not in school.
“Despite these efforts and meetings with parents, unauthorised absences continue to be higher than it should be, and youngsters learning is adversely affected as is their attainment.
“The responsibility in my view lies largely with the parents as they are clearly letting their youngsters down.”
Unauthorised absences accounted for 49,597 days lost in Angus schools in 2015-16, which increased to 57,703 in 2016-17 and 60,646 in 2017-18.
The primary table was topped by Hayshead in Arbroath with 5,691 days lost to unauthorised absences since 2015-16 which has also increased year on year.
An Angus Council spokesman said: “Schools are required by law to maintain an accurate record of the attendance and absence of each pupil and all our schools have procedures to monitor children and young people’s absence from school.
“Parents are responsible for ensuring that their children attend school regularly and arrive on time and are also responsible for ensuring the safety of their children on their journeys to and from school.
“If a child does not arrive at school, and there is no reasonable explanation provided for his/her absence, staff will investigate their whereabouts and safety.
“Parents are encouraged not to arrange family holidays during term time.
“Where this is unavoidable, they must provide their head teacher with information of the dates when their child is to be absent from the school.
“Except in cases of emergency, appointments for children to attend the dentist or doctor should be made out with the school day.”
Travel agents confirm the cost of holidaying in Britain and abroad soars after term ends.
Parents say they are forced to take their children out of school because of massive holiday price hikes that accompany “peak season”.
In 2017 a father lost a court battle after challenging a £120 fine for taking his seven-year-old daughter to Disney World, Florida.