Business for Britain: UK firms and the EU Single Market
1 November 2013 Last updated at 14:17 GMT
The costs of complying with Single Market regulations outweigh the benefits of being in the EU, said nearly half of the business leaders surveyed by the new Business for Britain group.
Chairman John Mills said there were a lot of EU countries who did not want Britain to leave, but British businesses would rather see decisions made in London, not Brussels.
The campaign group is in favour of changing Britain's relationship with the EU, and Mr Mills said finding a solution to the eurozone's problems gave UK firms an opportunity "to redefine the role we are going to have".