Eight out of 10 households throw out personal information with the rubbish that could enable fraudsters to steal their identity, researchers say.
A search of bins for a national anti-fraud campaign found discarded bank details, national insurance numbers, mortgage documents and copies of passports.
Credit card numbers with expiry dates and signatures were found in one in 10 bins. A blank cheque neatly ripped into four pieces was also spotted.
Experts say a date of birth, mother's maiden name, password or even an unopened letter can be as valuable as cash to experienced fraudsters.
Criminals use the stolen personal information to open bank accounts, buy goods or apply illegally for credit cards, mobile phones or state benefits.
The research was conducted for National Identity Fraud Prevention Week, a government-backed campaign to remind people to keep personal details secure.
It's partly down to the fast-moving pace of society, said campaign spokesman Tyron Hill. We never have time for anything. Taking care of paperwork seems to be pretty low down on people's priorities.
All private documents and letters should be shredded, bank statements checked for unusual payments and important papers locked up at home to deter burglars, he added.
The growth of Internet shopping, banking and socialising has increased the risk of identity fraud, which campaigners say is worth 1.7 billion pounds a year in Britain.
People should never reply to emails asking for personal information and should install a firewall and anti-virus software on their computer.
Don't click on links if you don't recognise them, Hill said. If you're using social network sites like MySpace and Facebook, you should be careful about giving out personal information.
Home Office Minister Meg Hillier said identity theft often funds other crime such as drug trafficking, illegal immigration and benefit fraud.
Identity fraud is a serious problem and is often the tip of the iceberg, she said. For more details visit: www.stop-idfraud.co.uk/