The pass rate of next week's national A-level results is likely to exceed 97 per cent for the first time, a TES analysis reveals.
The results are expected to receive a further nudge with the proportion of A grades increasing slightly from last year's figure of 25.3 per cent.
Any increase in the pass rate is likely to lead to fresh headlines about falling standards.
However, heads' leaders point out that they offer no direct evidence of dumbing down.
Martin Ward, deputy general secretary of the Association of School and College Leaders, said any gradual rise in the results reflected the fact that teachers were getting better at preparing pupils for exams.
He said: "Slight increases over the years probably reflect the fact that schools, colleges and their students are becoming better adapted to the particular examinations regime they are working with.
"They do not show that standards have been lowered."
The predictions come from a comparison of A-level results over the past five years with national scores of AS levels taken by the same students the year before.
Pass rates at A-level are typically just over nine percentage points higher than they are at AS, reflecting the fact that students tend to drop out of A-level subjects if they are doing poorly at AS.
Last year's pass rate at AS was 87.8 per cent. This suggests an A-level pass rate in this summer's exams of just over 97 per cent, compared to a 2007 figure of 96.7 per cent.
At A grade, the pattern is slightly different. The proportion of AS exams awarded the top grade has remained broadly constant in recent years.
In 2007, the top grade proportion stood at 18.5 per cent, compared to 18 per cent in 2002.
By contrast, the proportion of A grades at A-level has risen much more sharply, from 20.7 per cent in 2002 to 25.3 per cent last summer.
The small increase in last year's AS results suggest a small increase in this year's A-levels.
See next week's TES for the full results from key stage 3 and A-level.