Unhappy parents believe Aldi have changed their award-winning nappies to make them less absorbent.
Some claim the new range are smaller - and increase the chances of leaks.
The supermarket have been slammed in a Facebook group after their award-winning nappies suddenly 'shrunk'.
Aldi deny the new batch has less absorbency and say they are proud of their affordable product.
According to Which? their nappies are some of the best value on the market with mums and dads able to buy then from 5p each.
But one mum wrote: “I use both 4 and 4+ for my twins but opened a packet of 4+ that I bought last week and they are different from what they normally are.
“The feeling is different (softer), the green is paler and most importantly they are smaller and less absorbent (as I found out this morning as my daughter was wet through and this has never happened) than they usually are.
“There also seems to be less stretch in the fasteners.
"You can also see in the second picture that if I match up the line of the green waistband at the back, the waistband is longer but the actual absorbent ‘nappy bit’ is significantly smaller.”
One mum agreed, saying: “I’ve used Aldi nappies on my daughter since birth never had any problem until about ?1 month ago she was soaking through.
"I’ve now moved onto Tesco Fred and Flo nappies.”
An Aldi spokesperson defended the new range but said they were always happy to receive feedback.
“As the UK’s largest own-label nappy brand, our customers buy over a billion award-winning Mamia nappies each year," the store said.
“We made some improvements to our nappies last year, including improving absorbency and ensuring a more even distribution of fluid to give a better fit and reduce sagging.
"We’re always grateful for customer feedback, which helps with future product development.”