Almost half of schools inspected in the first three months of this year were found to be not good enough, new figures show.
Statistics published by Ofsted reveal that 34% of the 1,964 schools visited by inspectors - 658 in total - between January and March were only satisfactory.
And a further 9% - 183 - were judged to be inadequate and either given a notice to improve or put in special measures.
This is higher than the previous academic year (2010/11) when 6% were found to be inadequate.
Ofsted said this is likely to be because, since January, schools have been inspected under a new regime.
Under the system, schools previously rated "outstanding" are now not routinely inspected and those considered "good" are visited less frequently.
It means that Ofsted is now inspecting more weaker schools as well as good and outstanding schools where potential concerns have been identified.
The latest figures also show that 7% (144 schools) visited between January and March were found to be "outstanding", while half were declared "good".
An Ofsted spokeswoman said: "It is encouraging to see 50% of schools inspected since January were judged as good and 7% outstanding.
"Ofsted's revised school inspection arrangements from September 2012 will aim to identify in particular inadequate and satisfactory schools that need to do better.
"The grade 'satisfactory' will cease to exist and Ofsted will monitor and support schools that 'require improvement' and focus them on helping raise standards quickly."
The statistics also show that of the 144 outstanding schools inspected in this quarter, all were found to have outstanding teaching.
Concerns had previously been raised that a number of schools were being judged outstanding despite having teaching that was only considered good.
Figures for the final quarter of 2011 show that of 294 outstanding schools inspected, 122 were found to have teaching rated as good.
Ofsted Chief Inspector Sir Michael Wilshaw confirmed last month that, from September, only schools and colleges with outstanding teaching will be awarded this rating overall.
The move means that hundreds of outstanding schools could face seeing their Ofsted status reviews because their teaching did not get the top grade.