Principals say school health services need more funding after research showed they reduce student depression and the use of hospital accident and emergency departments.
Research by Auckland University has found 80% of schools have substandard health services, and most are under-funded and under stress.
The study says few schools are able to provide the on-site teams of doctors and nurses that have the biggest impact on teenagers' health.
The report says only 12 percent of schools have a health team on-site for most of the week, while about the same number provide nothing more than basic first-aid.
It says the best services are likely to be in low-decile schools, where government funding is focused.
Lead researcher Simon Denny said the research shows students at schools with quality onsite health services have a lower incidence of depression, suicide and alcohol abuse.
Dr Denny told Radio New Zealand's Nine to Noon programme on Friday that, while low-decile schools get some funding to provide health services, they are stretched.
"This sector is always under the knife and always underfunded - it is continually marginalised. For the staff working in these schools, sometimes they don't even know if they have a contract or a job the following year. It's a sector that really needs more support and some stability in funding."
Dr Denny said the Government funds on-site health services in decile one to three schools, but that doesn't go far enough and high-decile schools also need help.
Principals agree, including Peter Leggat from Wellington's Onslow College, who said an on-site service would encourage students to seek help and reduce the amount of time they spend out of class on visits to the doctor.
"It's a myth if people think that high-decile students don't have the same needs for health services as in any school. I would love to see us have the availability of a health professional, whether it be a nurse or a doctor on site here for even a couple of lunchtimes a week."
Health Minister Tony Ryall said the Government would consider increasing funding for school nurses.