It was a similar picture in London and the South West.
The lowest proportion of A grades was in north-east England (19.8% of entries) - an increase of 2.1 percentage points since 2002, which was also the lowest rate of improvement across the regions.
Northern Ireland students outperformed those elsewhere, as is usual, with 98.2% of entries passing and 35.4% awarded A grades.
In England 97.2% passed with 25.6 awarded A. In Wales, 97.6% passed and 24.1% achieved an A.
Mike Cresswell, director general of the AQA exam board, said the regional breakdown showed a "long-standing historical pattern".
"There will be all sorts of explanations for the differences and they won't all necessarily lie in the education provision in the regions," he said.
"The things that affect how young people perform in school are many and varied."
John Dunford, representing head teachers in the Association of School and College Leaders, said the regional breakdown in England did not surprise him, because it reflected the socio-economic make up of the country.
"I don't think it tells us very much more than wealthier people and higher social classes live in the South West and the South East, though that doesn't detract from the achievements of students in these areas," he said.
"There are also many more independent and selective schools in the southern part of the country and any additional improvement in selective schools is bound to be reflected in regional statistics."
He said the government deserved credit for the improving performance in London through its "London Challenge" programme.
And he added that his personal experience as a head teacher in the north east of England made him think lower parental aspirations for children was an important factor in the results.
Schools Minister Jim Knight said: "The exam boards themselves say this crude data on A-level performance in the regions would need more analysis before you can draw any significant conclusions.
"Across the country many more young people are getting valued A-level qualifications, especially in the priority subjects of English and maths.
"We do know that the improvement rate for overall A-level passes is the same or faster in the North West than in all of the southern regions.
"We also know that exam results in London are now higher than the national average following years of underperformance."
There were a record 827,737 A-level entries and 1.13 million AS-levels this year from more than 600,000 students.
The rise in entries for A-level is being attributed to more students choosing to do four A-levels rather than three, according to the Joint Council for Qualifications (JCQ), which released the results on behalf of the exam boards.
Conversely, one of the reasons given for the rise in the pass rate and in the proportion of A grades awarded is that AS levels are proving to be a "good staging post", with many students choosing to drop their weakest subject when they move into the second year of their A-levels.
The moment when A-level students find out their grades
Data released by the boards are seized upon for indications about the "health" of various subjects.
Increases in the number of entries for maths, science and some modern languages are a cause for celebration, say the exam boards and the government.
Entries for maths rose 7.5% from last year, to 65,239 - while further maths was up 15.5%, to only 9,483 entries.
Today's results for science and maths A-levels give us reason to be encouraged
Martin Rees, President of the Royal Society
Entries for chemistry were up 3.5%, those for biology were up 2.7% and those for physics rose 2.3%.
Mr Knight said: "I heartily congratulate all students who have successfully completed their A-levels and thank teachers for their hard work.
"More pupils are now passing maths A-level than at any time in over a decade. It's crucial for society that we have talented mathematicians and maths is essential for science and innovation."
Martin Rees, president of the Royal Society - the UK national academy of science - said: "Today's results for science and maths A-levels give us reason to be encouraged.
"Maths and further maths have continued their robust recovery with the numbers of students taking these A-levels increasing for the fifth year in a row. This is a welcome pay-off for the serious efforts made in recent years to boost this subject."
As the results were announced, the government explained how it was making A-levels more challenging.
Following successful pilots, tougher A-levels will be available to all from this September.
One change involves doing an "extended project", worth the equivalent of half an A-level. More than 1,400 students have been involved in a pilot with exam boards.
And students starting A-level courses in September will become the first to be eligible for the new A* grade when they are awarded to those attaining more than 90% in 2010. The first pilot versions have been awarded this summer.
The changes followed criticism that the rise in the number of A grades at A-level meant universities could no longer spot the brightest students.
The results statistics released on Thursday relate to exam entries, not students. The school-by-school breakdown - the "league tables" - is due to be published in January.
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