The move is in response to the Government placing caps on funding supplied to universities.
As a result, universities have decided to restrict entry to their courses in 2011.
In a recent newsletter to parents and pupils, John McGlashan College careers adviser Peter Manins said universities would now examine the year-13 results of all prospective secondary-school entrants and take only those with higher pass rates.
"Formerly, the minimum entrance requirement was 42 credits at NCEA level 3, but this will no longer guarantee entrance into most of our universities."
Kaikorai Valley College, Otago Boys' High School, East Otago High School and Cromwell College pupils had been advised in school newsletters of the changes.
Victoria University in Wellington has devised a scheme whereby each year 13 pupil is required to take their best 80 credits and calculate a score where each grade achieved with excellence is worth four points, merit is worth three points, and each achieved grade is worth two points.
All pupils achieving a score of 120 points or better will be guaranteed entry to Victoria.
Mr Manins said Auckland and Massey had similar systems.
Canterbury, Lincoln and Waikato Universities had made no changes for entrance in 2011, but were likely to do so for entrance in 2012, he said.
The University of Otago's new entrance policy is still to be finalised, but it has established a two-tier enrolment system.
The university council recently decided secondary pupils with strong academic records would be offered guaranteed entry.
Those falling below that standard would have to apply and take their chances based on the number of places available.
"Enhanced admission" places would be offered to Maori and Pacific Islanders who do not meet guaranteed entry criteria.
Under the new policy, pupils would be offered guaranteed entry based primarily on their year-12 academic results because year-13 results are not available until mid-January of the year they would start university.
"Tier two" pupils would be offered places based primarily on academic results, but other factors could be taken into account.
Academic deputy vice-chancellor Prof Vernon Squire, who headed the working group, said some details had not yet been finalised.
These included what factors would be looked at when considering whether to accept "tier two" applicants.
Mr Manins said the implications of these changes were obvious.
"Some merits and excellence are now required to ensure entrance into university.
"For restricted entry courses like medicine, law or engineering, a very good collection of merits and excellences at year 13 is required."
Kaikorai Valley College principal Philip Craigie had concerns about the changes.
"I think people's learning takes place at different times in their life.
"Some people don't do so well in school, but go on to do wonderful things at university - and vice versa."
