Oxfam is calling on British women to donate their unwanted bras because of the high price they raise for the charity in West Africa.
British women are hoarding nearly £1.2 billion worth of unworn bras, or nine each bought for around £16, according to Oxfam.
The charity's Big Bra Hunt aims to collect one million bras during April with the support of celebrities including Dame Helen Mirren, Zoe Ball and Miquita Oliver.
Many of the bras will be sold in Oxfam's UK high street shops to raise money for the charity's work worldwide while others will be sent to the charity's Frip Ethique (ethical second-hand clothing) project in Senegal.
The project trades unsold clothes from Oxfam shops and provides employment for disadvantaged women in the area.
Oxfam said the complex manufacturing required to make bras meant very few developing countries produced their own, making them one of the most desirable items in West African second-hand clothing markets.
Dame Helen Mirren said: "I'm sure many women have a number of bras stowed away left untouched for years. The Big Bra Hunt really highlights how every last item donated to Oxfam can be used in a truly unique way, making a real difference to people all around the world."
A poll for Oxfam found that a third (33%) of all women who have bras they no longer wear keep them because they forget they own them, and 10% did not know charities accepted them.
Oxfam's head of retail brand Sarah Farquhar said: "This research really shows the vast number of bras women in the UK leave forgotten and unloved in their drawers.
"The Big Bra Hunt hopes to highlight that whilst these bras may not be of use to the average British woman, the jobs created and profits made from the trade and sale of these bras provide a unique opportunity for women in West Africa to provide for their families, send their kids to school and afford vital medicines."