Jeans for Genes is asking people across the UK to wear denim for a day in a bid to raise £2.5 million.
The campaign, which is being managed by Great Ormond Street Hospital, is urging businesses and schools to join in by allowing employees and pupils to "Be a Star
for the day by donating £1 for wearing their jeans.
Women's clothing retailer Dorothy Perkins is running a special promotion from 27 September until the actual day on 4 October, with £1 from every pair of jeans purchased being donated to the appeal.
The event is to be sponsored by HIT Entertainment, owner of children's TV show Bob the Builder, which will provide educational packs for nursery and primary schools. It will also donate a share of the video sales of Bob the Builder's Live Stage Show between 7-31 October.
Actress Leslie Ash, Holby City actor Jeremy Edwards and Bob the Builder are fronting the event for the charity, which includes pop star Robbie Williams among its patrons.
Proceeds from the day will be used to fund vital genetic research to help alleviate and cure childhood genetic disorders. Eight national charities including Great Ormond Street will benefit from the event.
According to the charity, one baby in every 30 born in the UK is affected by a genetic disorder or birth defect.