Three-quarters of teenagers failed to achieve C grades in key GCSE subjects this year.
Nearly one in five pupils in England did not score a single C, while half fell short of the mark in the three Rs.
Only 24% of teenagers scored Cs in a combination of the Government's most highly targeted subjects - maths, English, science and languages.
Ministers said the figures marked major improvements over the last decade but admitted that results would have to rise twice as fast to meet their targets.
Schools minister Jim Knight said: "We need to do roughly twice as well as we have been doing in the rate of improvement.
"We have averaged around 1% a year across the last 10 years and we need to double that."
By 2011, the Government wants 53% of pupils to achieve five C grades or better in GCSE subjects including English and maths.
The results for exams taken by 650,000 pupils this year showed 61.5% scored five A*-C grades, a rise of 2.3 points on last year.
But when English and maths were included, only 46.5% scored five Cs or better. Nearly one in five state school pupils - 18.9% - failed to get a single C grade in any of their GCSEs.
But the minister insisted that the overall improvements were significant. "Whatever the carping from the usual doom-mongers, 470,000 more young people since 1997 have got a better start in life," Mr Knight said.
