MARS is ditching plastic packaging and going back to using paper — like it did up until the mid-1970s.
It means bars will feel a little different, but company bosses promise it will not affect the freshness — or customers will get a refund.
The trial starts in 500 Tesco stores next week.
If it is a success, the new wrappers will be rolled out to all retailers and the brand’s other favourites such as Bounty, Galaxy, Maltesers, Milky Way and Snickers.
Such a move across Mars’ full range would save thousands of tons of plastic a year going to landfill, with the new wrappers easily recycled.
Rival Nestle has been using paper wrappers for its Smarties brand worldwide since January 2021.
Mars bars were sold in hand-wrapped paper from their launch in 1932 up until 1977.
Back then, factories full of workers did the wrapping.
But it has been a struggle to get machines to do the same job with anything other than plastic, which customers are used to.
Shelf life has also been an issue as plastic keeps out moisture and air much better than paper — keeping it fresh for years.
Before the mid-70s, customers did not mind if older chocolate developed a white coating, which is harmless.
Adam Grant, of Mars Wrigley UK, said it had taken Mars nearly two years to get the right paper and adapt factory lines.
The firm has had to keep a “tiny” amount of plastic on the inside of the wrapper, but this does not stop it being recycled or breaking down quickly in landfill.
Mr Grant said: “It is great we are able to trial a return to paper that is recyclable, but with the advanced, innovative technology that ensures the product quality is not compromised.”
Plastic wrappers used for chocolate, sweets and crisps can take around 20 years to decompose — and sometimes much longer.