The Auckland Secondary Schools Principals' Association says Auckland needs 6,500 high school teachers over the next 20 years to cover a predicted shortage.
A large number of teachers are fast approaching retirement age and there is simply not enough quality graduates to fill the void.
Technology, science and maths are particularly short.
Stephen McIvor speaks to Auckland Secondary Schools Principals' Association Vice President Richard Dykes, who is also the Glendowie College principal, for his thoughts on how serious this problem is.
He says the problem is already bad.
We've got schools really struggling to fill a number of positions.
"[Schools] are desperate now and it's going to get worse," Mr Dykes told RadioLIVE.
Listen to the full interview with Richard Dykes above.