Schools and colleges are furious about the proliferation of new assessments, which cost up to pound;95 each and will be taken by thousands of students this year.
They say preparing for the exams means more work for students, adding to their anxiety, while those from poorer backgrounds may not apply because of the cost. Sixth-formers applying for medicine could end up paying pound;181 to take separate admissions tests, set by different universities, while companies are charging up to pound;495 for test coaching.
Some of the new exams, launched because universities feel they cannot rely on A-levels to select students, must be taken in schools. At least 11 tests have been set by leading universities selecting for sought-after subjects.
There are three tests covering medicine, with students having to do the one set by their chosen university.
Oxford and Cambridge set tests for subjects including history, languages, maths and physics.
Meanwhile, uniTEST, a "generic" test which could eventually be used to assess suitability for arts and science subjects, is being trialled by seven universities this year, including Exeter, Edinburgh and Warwick.
The advent of the tests comes with universities already poised to receive more A-level data than ever before. From next year, they will be able to make offers conditional on students' results in individual modules, as well as on the exam as a whole.
Neil Hopkin, principal of Peter Symonds college, Winchester, which has 2,750 A-level students, said: "The people who set these tests are not taking into account the strain on students."
Sue Kirkham, president of the Association of School and College Leaders, said: "A lot of our members feel that many pupils are not going to bother with these tests. It costs money and those from better backgrounds will do better because they can afford coaching."
Natalie Crawford, 17, an AS student at Portsmouth grammar, who is likely to take at least one test for medicine, said: "This is quite a scary prospect when you think about all the other things we have to do." She has already completed three weeks' work experience in hospitals and took five AS-levels this summer.
Geoff Parks, director of admission for the Cambridge colleges, said that Oxford and Cambridge reject more than 10,000 students a year with three As at A-level. Cambridge is involved in six of the tests.
He said that without them, admissions would be "totally random" in some subjects, because neither A-level and GCSE grades nor school references could be trusted to reveal the best students. Pupils now face 105 assessments during their school careers.