Traders in the shadow of a new superstore claim they have lost up to half their business since it opened a month ago.
And some fear plunging takings, since Tesco opened its new Hove store, could drive them out.
They say parking problems and longer pedestrianisation hours in George Street have led to the number of shoppers falling dramatically.
Now traders have called a crisis meeting to discuss the situation.
They want Tesco and city council bosses to launch an urgent review of parking and pedestrianisation.
Tesco customers can use its car park for two hours if they spend more than £5 in the store but business owners say that is not enough time to allow people to visit other stores after doing their shopping.
Dee Borall, of New Look in George Street, said: "My own takings are down and, in some cases, other businesses are down by 40 or 50 per cent.
"It has happened because we lost the Haddington Street car park because of the Tesco redevelopment.
"The council has also extended the time George Street is pedestrianised to 6pm so no cars can park here until the shops shut."
Maurice Lambert, owner of nearby Heebie Jeebies restaurant, said: "Our takings are down by £1,000 a week and there are others which double that.
"There is only so long you can go on with those kind of figures."
George Street butcher Terry Burt said: "The nearest alternative car park to Tesco is at the town hall in Norton Road but people want to be able to park closer to George Street.
"Many of our customers are elderly or mothers with young children who don't want to walk that far."
A Tesco spokeswoman said the company wanted to work with local businesses to find a solution.
She said: "We are more than happy to talk to traders about their concerns."
A Brighton and Hove City Council spokeswoman said: "The council will consider all the issues arising from the extended pedestrianisation and is concerned to hear traders are experiencing loss of business.
"However, we do need to see evidence of this."
The meeting takes place at Heebie Jeebies, George Street on Tuesday at 6.30pm.
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