Schools face lightning inspections in which Ofsted would turn up without warning under radical plans.
Inspectors will take more notice of "local" intelligence about the performance of a school, such as concerns raised by parents about the quality of teaching.
A pilot project will see the current 48 hours' notice before inspectors arrive cut to nothing to make the Ofsted system more effective and more efficient.
Chief Inspector of Education Christine Gilbert set out the plan in remarks to MPs. Speaking to the Schools Select Committee, she said: "We are considering representations from parents and pupils that inspections should take place without any prior notice.
"We will look at the practicalities of no-notice inspection as part of our planning for the new school inspection framework.
"At the heart of any new arrangements will be the observation of teaching and learning by skilled and knowledgeable inspectors."
The changes could come into force in 2009 and reflect concerns that the current "light touch" inspections, in which Ofsted visits are shorter, could fail to spot schools that take a turn for the worse.
There have also been fears that, even with just two days' notice, teachers are tempted to rehearse lessons for the Ofsted visit.
Inspectors want to see schools as they really are and giving teachers no notice before they turn up is intended to reveal a more accurate picture of standards.
