Massey University vice chancellor Steve Maharey wants universities to have a say in a review of entrance requirements.
The New Zealand Qualifications Authority is reviewing open access to university for those aged over 20 and the entrance standards required of younger students.
Mr Maharey says removal of open entry for older students would be a substantial change and would need to be done carefully if it went ahead.
He wants universities to be consulted to ensure no groups are prevented from going to university.
Tertiary Education Minister Steven Joyce says it's not a question of whether over-20s should study, but rather if there should be an academic prerequisite for them.