One childminder or day nursery is closed each week following complaints from the public, David Bell, chief inspector, said this week.
The Office for Standards in Education received 6,250 complaints between April 2003 and March 2004 and took formal action against almost 400 early-years providers in England.
These ranged from a creche at a large leisure centre where there was raw sewage on the floor to an unregistered childminder looking after 14 children in a dirty home without knowing their full names.
The most common concern raised about childminders was whether adequate police checks had been carried out on all people who came into contact with the children who were being looked after.
Nurseries were more likely to face complaints that staffing levels were insufficient. The minimum staffing ratios are 1:3 for children under two; 1:4 for two-year-olds and 1:8 for children aged three to seven.
Ofsted prosecuted four providers, closed 49, and suspended the registration of 122 during the period. The majority of suspensions were agreed with the childminders.
In one case, a childminder reported herself to inspectors after a child in her care swallowed illegal drugs belonging to her teenage son. She was cleared of intentional wrong-doing by a police and social services investigation and was allowed to continue to look after children after agreeing not to take children over night and to prevent them going into family bedrooms.
Despite the shocking nature of some cases and a recent expose by a BBC documentary, Mr Bell defended the quality of early-years provision and Ofsted's record since taking responsibility for childcare standards in 2001.
Two of the nurseries featured in the television programme have since been issued with formal notices requiring them to improve or face suspension, but Ofsted refused to identify which ones.
Before 2001, childcare standards were the responsibility of individual local authorities.
Mr Bell said more than 99 per cent of the 50,000 childcare settings inspected so far were judged to be satisfactory or better.
Of 3,422 Ofsted investigations during 2003-4, half resulted in no further action being taken.
Two in five resulted in informal action agreed between inspectors and the provider, and only one in nine resulted in formal action.
But Mr Bell said inspectors could not completely eliminate accidents or abuse.
"Regulations cannot guarantee that serious incidents will not occur. We are not able to monitor childminders and nurseries 24 hours a day," he said.
Anyone with concerns about a childminder or nursery should contact the Ofsted complaints line: 0845 6014772."Early years: protection through regulation" is available from www.ofsted.gov.uk