One-third of all student dismissals, temporary suspensions and stand downs from Rotorua schools this year were related to drugs.
Figures released by the Education Ministry show Rotorua schools stood down, suspended or permanently excluded misbehaving pupils 286 times this year.
Nearly 100 cases were for drug offences and eight of those students, all under 16, were permanently dismissed.
John Paul College principal Patrick Walsh said cannabis use was a huge problem in Rotorua.
"It's reasonably easy to get drugs _ there's quite a large number of cannabis growing [areas] close to Rotorua city.''
Numerous ``tinnie houses'' and the prevalence of cannabis in some families added to its availability, he said.
Mr Walsh, who also heads the Secondary Principals' Association, said many local schools ran health programmes and drug-education schemes to combat the problem.
Nationally, schools have stood down, suspended or permanently excluded mis behaving pupils more than 17,500 times between January 1 and October 16.
Nearly 2000 student disciplinary cases involved drugs. Around 10 per cent resulted in pupils' permanent exclusion
or expulsion.
But despite a fall in numbers in recent years, Mr Walsh warned drugs remained a serious issue in many schools.
Cannabis was the most common drug, but more students were using synthetic cannabis products or "party pills'', he said.
Case numbers peaked two years ago. More than 3000 disciplinary incidents involving drugs were reported to the
Education Ministry, with more than 350 students permanently excluded.
However, Mr Walsh warned that drug problems in schools had not diminished.
"It's just being masked because schools are dealing with it in different ways.''
More schools were now using restorative justice programmes before stand downs or suspensions were enforced, Mr Walsh said.
For example, the student may under take drug counselling, apologise to the school and their peers and take on community work.
Keeping students engaged in learning is also a top priority for the Education Ministry.
"All learners must be present at school so they can participate and engage in learning,'' senior manager Jim Greening said.
Mr Walsh also warned of the effects of drug use on student learning.
"Often they have short-term memory, they can become aggressive [and] socially isolated.''
The Education Amendment Bill, currently before Parliament, would make it illegal for schools to drug-test students if passed. Random drug searches involving sniffer dogs would also be outlawed.
The bill has been widely criticised by teachers and principals.
Mr Walsh said monitoring for student drug use helped ensure a safe school environment for pupils and teachers.
"Particularly those in technology _ if they're using skill saws and hammers and other equipment, they need to know the students are drug-free.''