There's concern the Government hasn't made mask-wearing compulsory for school children.
It's recommended for over 12s but not required, when school begins for most of the country on Thursday.
Rotorua Intermediate School Principal Garry de Thierry says told Mike Hosking he's worried because classrooms are confined spaces and not well-ventilated.
He says recommending mask-wearing isn't the same as mandating it.
"There are some real concerns that my staff have and also I'm sure our parents do to."