The value of lost pension pots has increased by £7billion in four years to reach a staggering £26.6billion.
Experts at the Pension Policy Institute (PPI) said savers are at risk of losing serious amounts of cash as a result.
But the good news is there are ways to work out if you have a lost pension - and how to get it.
People can lose track of a pension pot because they change jobs, name or move house without telling their pension provider.
Studies have shown that only one in 25 people instinctively think to tell their pension provider that they have moved home.
In contrast, around 89% think to tell their GP or dentist.
Yvonne Braun, director of policy, long‑term savings and protection at the Association of British Insurers, said: “The amount of money in lost pension pots has increased by 37% to £26.6billion in recent years, with people missing out on money that can make a real difference to their quality of life in retirement.
"It’s time to pay your pension some attention and use the resources available to track down any lost pots."
How to find a lost pension
The PPI said there are five simple steps people can take to trace their pension.
These are to retrace career steps, check old papers, check that details are up to date, check for any gaps in your pension history and to contact your provider.
You can track down lost or forgotten pensions via the Pension Tracing Service at gov.uk/find-pension-contact-details, or by calling 0345 6002 537.
The free service run by the Government has an online database of more than 320,000 pension scheme administrators.
You will need the name of an employer or a pension provider to use the service, although it will not tell you whether you have a pension or what its value is.
It provides contact details for pension schemes run by employers, as well as for private schemes organised by pension providers, so you can then get in touch yourself to find out the amount of savings you may have.
The site helps you navigate the maze of firms which have changed their name or been taken over by a new company.
But you will only be able to get details of your pension savings once a pension firm has established you are who you say you are and that you do indeed have a pension pot with them.
You should only use the Government website service because although some firms claim they can help, they charge a fee which you do not need to pay.
But beware of crooks who set up similar sounding rogue sites to get hold of your personal data in order to steal from you.
