The Qualifications Authority is under fire for allegedly denying help to students with special needs.
Disability advocates say some students could fail their NCEA exams as a result.
Students can apply for special help, including the use of a computer, rest breaks and writing assistance.
But NZQA denied this help to Tim Blackett and more than 500 other students this year who appealed NZQA decisions on applications for special exam conditions.
Last year 35 appealed.
This year 85% of the appeals were successful - including Blackett's. He has a learning disability called dysgraphia and exams are difficult for him because he cannot write for long periods.
"Studying doesn't really have a purpose when you don't have time to communicate what you've been learning," said Blackett, an NCEA student.
Blackett's mother is an educational psychologist.
"I've talked to psychologists across New Zealand and they're all reporting that there's a huge number of appeals put forward," said Rose Blackett.
Disability advocates have also received complaints.
"We want to open opportunities for disabled people like getting a job or going onto further education," said David Matthews, the head of CCS Disability Action.
"If we make it difficult for them to sit and pass examinations we're making it difficult for them to achieve a good life."
NZQA says there are no problems with the way special conditions have been applied this year but it is ordering a review of the whole process.
"We want to make sure kids aren't disadvantaged, and we also want to make sure there is no advantage when it's not entitled," said Richard Thornton, the deputy head of NZQA.