The Labour Party says it has figures showing tens of thousands of people referred to a specialist by their doctor never got to see one.
Labour's health spokesperson, Annette King, said new statistics showed 80,000 New Zealanders referred to a specialist by their doctor since 2010 never got to see that specialist, and were instead simply sent back to their doctor.
Ms King said the figures were supplied by less than half of the country's health boards, so the total number of unseen patients nationally would be far higher.
She said it was not the fault of the health boards or specialists, it was because the Government was squeezing health funding.
"We've had reports from patients who have been waiting for an assessment. They'd go back to their GP, the GP refers it back to the specialist, then they're sent back to the GP.
"This ping pong being played with patients' health is just unacceptable," Ms King said.
However, Health Minister Jonathan Coleman said 60,000 more patients each year were now being seen for their first surgical assessments than when National came into government in 2008.
He said in 2006 under the previous Labour Government about 25 percent of all GP referrals to specialists were returned to GP care.
Dr Coleman said the outcome of GP referrals had never been formally measured and the Government had to establish an initiative to see that they were.
"The first set of reliable information is due for release early to mid-2016," Dr Coleman said.
Phil Bagshaw, a surgeon and co-founder of the Canterbury Charity Hospital, said the unmet demand had been barely measured since health reforms came into effect.
"There is a massive amount of unmet need out there, we at the charity hospital every week, see many many patients who have been turned away.
They come back with what we call the 'Dear John' letter. Which is a letter from the district health board saying, 'we don't treat that now' and 'go back to your doctor'."
Bob Gregory-Hunt, who is in his 80s, said he had been been waiting for two years for a cataract operation at Christchurch Hospital and was frustrated at being repeatedly sent back to his GP for monitoring.
Mr Gregory-Hunt had seen a specialist but could not get a date for his operation.
"I've had several appointments in the hospital since, and they've looked at them and said 'yes, they're definitely on the urgent list', 'definitely on the list' and 'definitely on the list to be looked at next time'," he said.
"God knows what we're going to do. It's still on the list and that's as far as it's got."
Mr Gregory-Hunt said he was so blind he was constantly at risk of falls.