The country's drug-buying agency Pharmac has been slated in a new report.
An independent panel looked at how the agency makes decisions and found its approach disadvantaged Māori, Pacific, disabled people and those with rare disorders.
Decision-making was opaque and slow and there may be an excessive focus on containing costs, the report said.
The 25-year-old agency was underperforming and there was a perception New Zealand is falling behind other countries.
Several people told the panel Pharmac did not communicate well enough with patients when it switched from one medication brand to another or declined to fund a medication.
The review was headed by former Consumer NZ head, Sue Chetwin and commissioned by the Ministry of Health.
It did not provide recommendations but did find several major shortcomings.
However, it also said Pharmac did not give it all the information it needed to truly judge how it was performing.
"Pharmac zealously guards information about a host of operational and financial matters, making it difficult to measure the extent to which it is meeting its objectives," the report said.
Chetwin said they heard from doctors and pharmacists, including Māori and Pasifika health providers, the pharmaceutical industry and patient advocates.
But they were most grateful to those who told personal stories of how they, or their whānau, had struggled to get public funding for their medication.
"No review member was left unmoved," she said.
Cancer Society chief executive Lucy Elwood welcomed the report, saying it saw every day the stresses of patients and their whānau waiting for Pharmac to decide whether to fund a medication, when time was running out.
It was especially hard when they saw the drugs funded in other countries, she said.
The report found the agency had only 2.2 percent of staff who were Māori and did not pay enough mind to the Treaty of Waitangi or health problems that disproportionately affected Māori when making decisions.
Chetwin said Pharmac was a small agency of highly skilled people and the report was not intended to undervalue their hard work but to look at how it could do better.