Cambridge University has written to all schools and colleges urging them to continue to offer AS-levels in the wake of the government's decision to make them a standalone qualification.
The prestigious institution said it "strongly encourages" would-be applicants to take AS-levels in at least three subjects, arguing that the exams are of "significant educational benefit".
Under major reforms to the exams system in England from next autumn, AS-levels will be separated from A-levels to form a qualification in their own right.
It is part of a wider shake-up of A-levels which will see new courses introduced and sixth-formers no longer sitting exams after one year, but at the end of their two-year course instead.
In the letter, Mike Sewell, director of admissions for the Cambridge colleges, writes: "We have for some years been strongly of the view that, for A-level students, AS-levels taken at the end of Year 12 are of significant educational benefit.
"They allow students to assess their academic progress, review their A-level choices, and make appropriate higher education applications with confidence.
"Our own research, supported by a recent study by the University of Bristol, confirms that AS is a better predictor of success at university than GCSE."
He said that in the event the reforms go ahead as planned, they are urging the government to ensure that all students at English state schools are able to take exams at the end of Year 12 in all of the subjects they are studying for A-level.
"We strongly encourage potential applicants to take AS-level examinations in at least three, and preferably four, subjects, whether reformed or not, at the end of Year 12," Dr Sewell said.
He added that Cambridge is aware that some schools may not offer this option to students and is asking schools to state this in their Ucas reference for students' university applications so that it can be taken into account. Dr Sewell insisted that would-be students will not be disadvantaged if they do not take AS-levels.
"Our admission goal remains to select the best students, regardless of their educational regime," the letter says.
"We are committed to ensuring that no student is unfairly disadvantaged within our processes by the model of provision offered by their educational institution."
The move to decouple AS-levels has proved controversial, with universities, headteachers and MPs raising concerns.
Cambridge has previously warned that for admission to its courses, AS-levels are the best predictor of how well a student will perform in every subject except maths. It has also argued that the move risks damaging a decade's-worth of work to encourage more disadvantaged teenagers to
study at the institution.
Ministers have argued that universities learn little more from knowing teenagers' AS-level results in addition to GCSE grades and insisted that the reform should not affect university admissions.
Labour has indicated that it would reverse the move, which would mean that AS-levels would remain linked to A-levels.
Scrapping AS Levels may "scupper" social mobility: 22 February 2013
Independent schools could drop A Levels in protest against reforms: 19 October 2014