Doctors' fees for many school-aged children are too high, say Opposition parties which want more taxpayer money spent on bringing them down.
Ninety-five per cent of children under 6 can go to the doctor free.
But for children aged 6 to 17 the average fee nationally is $22.31 - and about 40 general practices in Auckland charge $40 or more for a consultation during office hours.
The Green Party wants a maximum fee of $11.50 set for this age group and further reductions later, in return for bigger subsidies from the Government.
Health spokesman Kevin Hague cited as evidence of the need, the finding in the 2011/12 national health survey that about 7 per cent of children aged 6 to 14 had been unable to see a GP for a medical problem because of the cost.
"We've got rising rates of [GP-preventable] hospitalisations for children. It's unacceptable."
Reducing cost barriers to primary healthcare saved spending on hospital care, Mr Hague said, and was good for the health and welfare of the community.
The Child Poverty Action Group supports moving towards free access for all children.
Labour's health spokeswoman, Annette King, also supported increased state funding to reduce fees for children, but said the problems in primary care went much deeper.
"It's beyond a little tinkering for 6- to 17-year-olds. We need to look at low-cost access overall so we can have enough money going into primary care for people who need low-cost access."
But Health Minister Tony Ryall said 93 GP clinics provided free visits for those aged 6 to 17.
"Over a third of all 6- to 17-year-olds enrolled with a GP are enrolled in very low-cost-access practices. The Government specially subsidises their GP visits, so these 240,874 young people pay $7.64 on average per visit.
"Young people's health is a top priority for this Government. We have ensured that 95 per cent of children under 6 can now go to the doctor free, day or night."
Child Poverty Action Group spokeswoman Dr Nikki Turner, a GP, said children's skin infections, for example, were readily cured in primary care but if not treated early could necessitate more invasive and costly care in hospital.
"I see this all the time. You get an infected mosquito bite, you get a bit of skin infection in there, or you get a school sore, or you get scabies from your preschool or school. You scratch, it gets infected. If it's a cost barrier to go to the general practice then the family will often wait and hope it goes away and then will present late."