Thousands had queued up as early as 5.30am to get their hands on Roberto Cavalli's glam outfits at crazy prices.
Four of the eight stores with the limited collection of leopard print thongs to party frocks had sold out by midday.
It took only 45 minutes for fashion hunters to clear the shelves of Cavalli's £199 gold beaded dress - similar to the one worn by Hollywood star Scarlett Johansson.
Even the blokes were getting in on the act in the men's department.
Leigh Herbert and Dan Hull, both 20, from Middlesbrough, spent £850 at H&M's flagship store in London's Oxford Street.
Leigh, a fashion student at Northumbria University in Newcastle, said: "It was so crazy when the doors opened, we were shaking.
"People were grabbing whatever they could without looking at the sizes."
At the Bull Ring shopping centre in Birmingham, every item had vanished within 20 minutes.
It was the same at H&M in Manchester, Glasgow and Dublin, where only a few stray pairs of tights and knickers were unsold by lunchtime.
Cavalli is the latest designer to team up with a chain store to push couture in the High Street.
Madonna's collection flew off the rails at H&M and model Kate Moss's collection added to Top Shop's street cred And like Madonna's clothes, many of Cavalli's designs went on sale on eBay that same afternoon with sellers hoping to get twice what they paid.
Italian designer Cavalli has many celebrity clients with Posh Spice Victoria among the most wellknown.
He is currently designing stage clothes for the Spice Girls' comeback tour.
Billi Mucklow, 20, who had queued up from 7.30am to grab a bargain, said: "Cavalli's so popular because all the celebrities wear his stuff.
"Everyone's seen Victoria Beckham wearing his animal print dress. I've got a black Cavalli dress at home which cost around £600 but that's strictly for special occasions.
"I'm really impressed with the H&M clothes, they're really good quality."
Magnus Olsson, H&M's managing director, was delighted.
He said: "I was really pleased with the reaction.
"We did expect it because this is our fourth designer collection and the previous three have been very popular.
"I was very excited to have Roberto Cavalli on board, he's very well known on an international level and his clothes are very inviting."
