Students at The Abbey School in Kent could be tested for drugs at school when they return after the New Year.
From next term 20 students every week will be selected randomly by a computer to be tested for drugs including cannabis, cocaine and ecstasy.
The samples will be sent to a lab and results returned three days later.
Parents have to agree to let their child be tested and so far most have said yes. Pupils must also agree to taking part in the test.
If a student refuses to be tested, the school says it will call in the child's parents for a chat.
Those picked to be tested will be asked to go to the sick room and have a sample taken from their mouth - a bit like wiping a cotton wool bud inside your cheek.
Dealers face expulsion
Students who test positive will not be expelled, but any found selling drugs will be asked to leave.
Head teacher Peter Walker said the school decided to introduce the drugs tests to improve the quality of life for all students.
"We do not have any bigger (drugs) problem than any other school. There's a chance we have even less of a problem because we are so pro-active," added Mr Walker.