Sensitive information on school pupils is being put at risk by staff who are taking it home with them, reports the BBC.
A survey of 933 primary schools found that almost half allow pupil data to be put on CDs and memory sticks and to be taken out of school.
The survey by school computing firm RM reveals only 1% of staff are encrypting the data they take home with them.
RM has blamed a lack of clear guidance, although the government says it has published advice for schools on the issue.
The survey comes after a string of data breaches by government departments, including the breach last month by HM Revenue & Customs, which put at risk the personal details of 25 million people.