Firefighters tackle a blaze at a Sussex school on average every nine days.
There were almost 200 fires at the region's schools in five years.
The fire service statistics reveal that from 1999 to 2004 there were 114 fires at West Sussex schools and 76 in East Sussex.
The national Arson Prevention Bureau says the majority of fires in UK schools are started deliberately.
Council and fire officers in Sussex said they were doing all they could to tackle malicious fires.
Martin Burrell, chief fire officer for West Sussex, said: "We have embarked on a programme of advice to schools linked to the police. It does concern us. Unfortunately it is on the increase nationally."
From 1999 to 2004, fires caused £453,000 of damage to schools in West Sussex.
Firefighters are lobbying for every school to have sprinklers installed, something West and East Sussex County Councils do not do at the moment but may reconsider following next month's election. Some schools have CCTV.
West Sussex County Council has an education worker who advises how to reduce the risk of fire damage.
A spokeswoman said: "We do take this matter extremely seriously."
Kathy John, arson reduction co-ordinator for West Sussex, said arson was an increasing problem but statistics were rising partly because schools and firefighters were working together to make sure every incident was recorded.
She said: "We encourage them to take every fire-setting event very seriously and we will attend."
Firefighters work with young people to teach them about the dangers of starting fires. Children at risk are nominated to take part in organised programmes.
Miss John said: "It isn't so much of a telling-off process. It is to educate them about the seriousness of the situation they are in and the consequences. Children play with fire from a very young age out of curiosity and many children who die in fires are involved with playing with matches. We try to target people at the earliest opportunity when you find they are interested in fire."
Two children under the age of five died in their own homes in West Sussex last year as a result of accidental fires.
Earlier this month there was a suspected arson attack at Tideway School, Newhaven, which destroyed property worth £1 million. Pupils have been taking lessons elsewhere but it is hoped they will be able to return to the school on Wednesday.
A Sussex police spokesman said: "We work closely with the brigade. I know Crimestoppers run an arson campaign for people to use the Crimestoppers line. We encourage anybody seeing anything suspicious around schools to get in touch. We would also encourage people to report any youths seen on school premises out of hours.
"Arson is an extremely serious offence and the courts will take the circumstances into account."
A Brighton and Hove City Council spokesman said: "We haven't had any major fires. Half of them are probably mischievous and half are electrical faults."
An East Sussex County Council spokesman said: "East Sussex compared to some authorities doesn't seem to have a huge problem. It doesn't mean to say we dismiss it as not a serious issue because it is."
Last year, the Government set up Arson Task Forces to tackle malicious fires.
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