EIGHT out of 10 childcare providers inspected last year must improve, the Office for Standards in Education says.
Ofsted took over inspections of nurseries, playgroups and childminders from councils in September 2001.
By September 2002, 50,000 of 100,000 groups and individuals had been inspected. Those who failed to meet requirements were often breaking health or safety rules or being run by an unsuitable person.
Childcare worker Patricia Hambrook had expected an Ofsted interrogation.
She runs three after-school clubs and a pre-school club in Waltham Forest, east London, for a Christian charity.
But inspectors had been a pleasant surprise and "genuinely interested".
"They didn't say that's rubbish. You felt everything they suggested was possible."
Ofsted also investigated 6,000 complaints, of which half required action.
It had to use its powers on only 100 occasions - mostly against illegal childminders.