More Diploma lines and levels are planned
A large majority of higher education courses in the UK - 80% - will accept the new 14-19 Diploma as an entry route, the government says.
But among more prestigious research universities in the Russell Group, the figure is just 40%.
Five Diplomas of differing levels were introduced last year in England, and more will follow.
The government said the acceptance was testament to the high quality of the Diplomas and the skills they provide.
The Diplomas are not meant to be of less academic value than A-levels, but the subjects available currently will not all contain content relevant to many of the courses at the more prestigious institutions.
Almost all universities have given statements to the Universities and Colleges Admissions Service (Ucas) explaining how they view them.
Bristol University, part of the Russell Group of 20 research-intensive institutions, says it will accept advanced level Diplomas.
"Advanced Diplomas are part of the National Qualifications Framework, and the university will view the general standard of preparation as being equivalent to existing Level 3 qualifications such as A-levels.
"Individual admissions tutors will, however, wish to satisfy themselves that Diploma applicants have developed study skills and subject knowledge appropriate to the programme applied for."
Most higher education institutions are saying they will accept Diplomas - but with similar caveats regarding what is taken on the specialised learning component of the Diploma.
But Cambridge University is more hesitant. Its statement to Ucas says: "We will be considering the acceptability of the new Diplomas for our courses on a case-by-case basis.
"Of the Phase 1 Diplomas, the advanced engineering Diploma is the only one which provides appropriate preparation for a Cambridge course, and will be accepted for engineering as long as you have taken A-level physics and the new Certificate in Mathematics for Engineering within the specialised learning component."
Oxford University has said the same.
Director general of the Russell Group, Dr Wendy Piatt, said it welcomed Diplomas as a means to "expand opportunities for potential students from a broader mix of backgrounds and educational experiences to progress to higher education".
But she said: "We want to be fully assured that any new Diploma lines are sufficiently robust and challenging academically."
The first five Diplomas (Phase 1) began in September 2008 in the employment sectors of creative and media, information technology, health and social care, construction and the built environment and engineering.
They are offered at three levels: foundation - equivalent to lower tier GCSEs, higher - like higher grades in GCSEs (not Scottish Highers), and Advanced - equivalent to A-levels.
Later this year teaching is due to begin in five more: land-based and environmental, manufacturing, hair and beauty, business administration and finance, and hospitality and catering.
More will begin in 2010 - in public services, sport and leisure, retail and travel and tourism.
Diplomas with the "academic" subject areas of science, languages and humanities are also planned, though last month the government said it would delay the introduction of its advanced level science Diploma by a year because of uncertainties about its content.
It said no other Diploma lines would be affected.
The government has also announced plans for "extended" Diplomas - these will be more challenging in a core of English and maths.
Ucas has decided that an Advanced Diploma will be equivalent to 3.5 A-levels and the Extended Advanced Diploma to 4.5.
Schools Minister Sarah McCarthy-Fry said the acceptance rate for the initial five qualifications was "excellent news".