Diners at Knightsbridge restaurant Mju paid as little as £7 for their food last week when they were invited to pay what they wanted.
The offer allowed customers who made reservations through online site Toptable to enjoy a three-course fine-dining meal without wine and pay what they believed it was worth.
They were given a menu with four starters, mains and desserts to choose from, all without prices.
Diners at Mju, which opened two years ago at the Millennium hotel, usually spend on average £37 each.
Director Alysoun Stewart estimated that most people paid about 20-25% below average, while a small proportion paid as little as £7.
She said the restaurant had more than covered its food costs and the offer had filled what would normally have been a quiet week.
She added: "There was a percentage of customers who didn't enter into the spirit and used it to get a cheap meal, but I think a lot of people who had never been to the restaurant before will come back."
Karen Hanton, director of Toptable, said the success of the offer had led to interest from other restaurants.
Source: Caterer & Hotelkeeper magazine, 28 August - 3 September 2003