The Ethics Group, a government advisory body, says DNA samples of those not convicted of a crime should be deleted from the police National DNA Database.
The current database contains 4.2m records, and these are never deleted, even if a person is never charged with an offence.
It is estimated up to 500,000 people who have profiles on the database have not been convicted or cautioned for a crime.
This number includes profiles of up to 100,000 children.
In its first annual report, The Ethics Group said there should be a straightforward system for innocent people to have their DNA records deleted.
It also rejected police demands for a national DNA database.
The government said it would respond to the report in the autumn, after consulting with the police.