Real ale campaigners are to lobby Parliament as part of a campaign to scrap the "damaging" beer duty escalator.
The Campaign for Real Ale (Camra) said that since the policy of raising beer duty by 2% above inflation was introduced by the Labour government, over 5,800 pubs have closed and the number of pub-goers has fallen by three million.
Camra said it will be the biggest campaigning event in its 40-year history, with over 1,000 of its members expected to take part.
Chairman Colin Valentine said: "Over the past 40 years there have been few threats to the UK pub industry as severe as the beer duty escalator, which is why so many of our members from across the country have travelled to Westminster to participate in today's lobby.
"Even after a Government e-petition reaching 100,000 signatures, and a Parliamentary debate where MPs present unanimously backed a review of the beer duty escalator, the Government do not appear to have woken up to the crippling social and economic impact their actions are having on valued community pubs.
"With the nation's pub closure rate back on the increase, what the Government should be doing is looking at ways to alleviate the burden on struggling pubs, and further recognise their importance as community assets.
"Such a huge decline in the number of regular pub-goers is a critical reminder that change needs to happen fast to prevent irreparable damage to community life in the UK, and to save the nation's proud pub-going heritage from being taxed into oblivion."
The escalator, introduced by then-chancellor Alistair Darling, increases the price of a pint by 2% above inflation, and is due to last until 2014-15.