Dundee High School has expelled three pupils and suspended 14 over cannabis and e-cigarettes brought into the school.
Writing to parents on Friday, rector Dr John Halliday said: “Three pupils in F3 have now left the school for their involvement in this incident.
“A further pupil has also been suspended and given a final warning but will be allowed to return to school after half-term, subject to strict monitoring of behaviour.”
The letter came just a week after parents and guardians of children at the fee-paying school were informed of the incidents involving cannabis and the distribution of e-cigarettes.
The school contacted police, Dr Halliday sought to reassure parents and guardians that no pupil still at the school is under investigation by police.
He added: “I would also like to confirm that, having conducted our own thorough and vigorous investigation, interviewed those involved and decided on which sanctions are appropriate, we now consider this matter to be closed.
“As you are aware we were also looking into the use of e-cigarettes in school by some F3 pupils.
“Again this is something we take seriously and as a result 13 pupils have been suspended and given clear warnings as to their future involvement in such incidents, and guidance to help them make good choices.”
Dr Halliday added that he was “disappointed” that a small group of students had let down the reputation of the school, which received high praise during a recent inspection.