Customs-style hi-tech detectors are being used to check school children for drugs.
Several boys were found to be in possession of cannabis
Ten schools in Kent have tested the £30,000 Ion Track Tester, an electronic device which can pick up traces of class A, B or C narcotics.
The county council, which is running the scheme together with Kent police, said it could be extended elsewhere, after a largely "positive outcome".
Paul Carter, the county councillor in charge of education, said the actions were not aimed at making arrests, but to "offer support" to pupils before they became addicted.
'Heads in favour'
He added: "We don't want drugs on school premises. If you go to an airport, you expect to get searched for drugs and explosives.
"If you go to school, why shouldn't you be expecting to be searched for drugs?"
He added: "The positive good outweighs the negative aspects.
"We have talked to head teachers in schools not taking part so far. They are in favour of the scheme."
The Ion Track Tester, developed in the US, can detect illegal drugs within five seconds of taking a swab.
Several boys at secondary schools in the Tunbridge Wells, Tonbridge and Maidstone areas of Kent were found to be in possession of marijuana.
The use of the machines is part of an ongoing anti-drugs project called Operation Caddy, which has also used sniffer dogs to search school premises.
A Department for Education and Skills spokesman said: "Drugs can have a devastating impact on young people's lives. Even small amounts can affect their health and education. Drugs lead to major disruption within schools themselves.
"Schools have a vital role to play, alongside parents, in educating and helping young people to protect themselves from the risks and harm of illegal drugs, alcohol and tobacco."