The latest secondary school league tables for England show about 300 schools are below the government's benchmark target for GCSE exams.
More than 50 of these struggling schools, where fewer than 30% of pupils had five good GCSEs including English and maths, have already been closed.
In 100 schools there were 100% of pupils achieving this benchmark.
The results mean fewer schools failed to reach the GCSE target - down to 247 this year from 439 the previous year.
The lowest performing school was St Peter's Church of England in Chelmsford - where only 8% made the grade.
The highest scoring school was Invicta Grammar School in Maidstone, Kent.
Its pupils averaged 764.5 points apiece, compared with the 214.9 at St Peter's.
The figures also show that 46 of these struggling schools got worse results in 2009 than in 2008 and 15 schools got the same results.
The best A-level performance - for the third year running - was at another Essex school, Colchester Royal Grammar.
Its pupils averaged 1354.7 points. This was slightly less than last year, but still was the equivalent of just over five grade As per head.
Colchester, a selective grammar school, describes the academic achievement of its pupils as its "raison d'etre", with exam success its key performance indicator.
The most improved region is London - where 54% of pupils achieve the benchmark of five good GCSEs including English and maths. This stood at 29.9% in 1997.
The government has made a point of targeting, in a controversial National Challenge programme, the schools with less than 30% GCSE attainment.
Two months ago the Schools Secretary, Ed Balls, said he expected local authorities to show they could "take tough decisions to do what is right to drive up standards".
He said he was concerned that some were not using the powers available to them, for instance to issue warning notices to schools to improve or face closure or takeover by a more successful neighbour.
These show that a whisker over half of all pupils in England's state schools, 50.7%, attained the benchmark of five good grades with English and maths - regarded as the key to employability or further study.
The government has a target to increase the proportion to 53% by 2011.
The league table statistics also show the gap between girls' and boys' performance has narrowed slightly, by 0.7 percentage points.
In 2008, 44.4% off boys achieved five GCSEs A*-C, including maths and English - this rose to 47.1% in 2009. For girls, the figures stood at 52.4% and 54.4% respectively.
A new feature of the tables this year is an alternative "progress measure" showing what percentage of pupils in each school made the sort of progress they were expected to between leaving primary school and completing their GCSEs.
This assumes pupils who achieved the level expected of an 11-year-old should go on to get at least a C at GCSE.
The government has plans to introduce school report cards. The Conservatives would keep annual league tables - a feature of England's education system that is not present in other parts of the UK.
Schools Minister Vernon Coaker said: "A decade ago, just 35% of children left school with five good GCSEs including English and maths - now with our best results ever, it's 49.8%.
"In fact, the average school performance in 1997 is now roughly where we put the absolute bottom bench mark expected - the entire system has shifted up a level and we are determined to keep it moving."
But the Conservatives said there were 874,346 children in schools in which less than half the children made the required level of progress from the age of 11 to 16.
Shadow children's secretary, Michael Gove, said: "We want to close the educational gap between the fortunate few and the rest.
"That's why we've outlined plans to improve the quality of teaching, give heads proper powers to crack down on bad behaviour and allow educational providers to open a new generation of independently run state schools with the characteristics that parents want, like smaller class sizes."
Teachers' unions once again condemned the tables.
Christine Blower of the National Union of Teachers said the figures did however show that secondary schools really were making "a fundamental and positive difference to young people's lives", particularly those from deprived backgrounds.
But the head of the Association of Teachers and Lecturers, Mary Bousted, said: "The bottom line is that our exam system continues to fail too many of our young people."
Too many still left school or college lacking the qualifications and skills they needed for further education, training or employment.
"In our tough economic climate and with the rapidly changing job market it is even more important that young people leave education with the desire and ability to continue acquiring skills throughout their lives."