Parents say an online survey for England's children's services watchdog asked pupils to give their postcodes, potentially exposing them to danger.
Children were told to do the poll online at school
The National Confederation of Parent Teacher Associations says it supports parents who are asking Ofsted to remove data provided by their children.
It warns that paedophiles might be able to access details of youngsters who have revealed they are vulnerable.
Ofsted says the information is useful to improve services and is anonymised.
The survey - called Tellus2 - has been completed by 120,000 school children across England in the past few weeks.
Primary and secondary schools have taken part on a voluntary basis, selecting classes in Years 6, 8 and 10 to take part.
Ofsted says it a valuable tool for getting the views of children, which will help monitor how local authorities are performing and inform decisions on service provision.
The poll covers many aspects of a child's life, from their health and diet to what they think of local amenities and whether they have been bullied.
It has already attracted criticism from teachers' and head teachers' representatives for asking children whether they had had a drink or lived in single parent households.
Pete, a father from Stockton-on-Tees, was angry that his children had been asked to enter their postcodes on the survey. He had not been asked to give permission for them to take part.
"To make things worse, my son actually objected to entering his postcode on the web, as I have ingrained into him that under no circumstances should he enter personal data into any website, but was made to enter the data by the supervising teacher," he said.
SAMPLE QUESTIONS - PRIMARY
How much fruit and veg a day?
Have you ever had an alcoholic drink?
Have you been drunk in past month?
Have you ever smoked?
How safe do you feel from hurt at school and at home?
Who do you live with?
Does the mum or step-mum you live with have a paid job?
What do you think of your area?
What would make it a better place to live?
Pete, who asked for his full name not to be published, asked Ofsted to remove data concerning his children - aged 11 and 13.
They did - but he says the fact that they were able to do this shows they were capable of identifying individual survey respondents.
"Imagine that there is someone with legitimate access to this data, they search for children that report 'home problems', pick up the postcode, and in no time at all have access to thousands of already vulnerable children and exactly where they live, a paedophiles' wildest dreams come true," he said.
As an IT consultant, he said he knew there would be a wide range of people with access to the data.
"As well as those working with the data, there will be literally hundreds of others working in IT areas who will have 'legitimate access' to the files."
Parents should all ask for their children's responses to be removed, he said.
The call has won the support of the National Confederation of Parent Teacher Associations.
Margaret Morrissey, from the organisation, said: "A large proportion of parents will have concerns. It's important that we know where the information is and how easily it is available.
Pupils in Years 6, 8 and 10 took part
"If someone is of that mind and is determined it's not impossible to get information about the little girl who lives next door.
"We support parents who ask Ofsted to remove their children's data. I am not casting aspersions on Ofsted. This survey was well-intentioned but it has not been extremely well thought out."
Ofsted supplies local authorities with a letter which can be sent out by schools to parents explaining what the poll is for and about. Parents are not asked to give permission.
An Ofsted spokeswoman said local authorities had asked for postcodes to be included to enable them to make comparisons between different areas.
"In order to provide useful information to local authorities, as well as summary analysis at local authority level, an anonymised version of the 'raw data' will be provided to local authorities if quality assurance testing demonstrates that the information is robust and it doesn't introduce risk of individuals being identifiable.
"This may include the first three digits of the post code only. This methodology was developed in consultation with, and taking into account, the advice of [market researchers] Ipsos Mori as consultants.
She added: "The questionnaire asks children and young people to enter their postcode if they are willing to do so and if they know it. Children and young people are not asked for their names.
"The questionnaire is completed on-line and submitted by the young person direct to Ofsted. Access to the responses and postcodes can be viewed by a small restricted group within Ofsted."