Business lobby group British Chambers of Commerce (BCC) says most UK companies want to stay in Europe, with some powers brought back home.
The BCC surveyed 4,000 businesses and found 64% of those who responded said they favoured making adjustments to the UK's agreements with the EU.
Employment law was the number one area they wanted opt outs from.
However, the survey also found that almost one in five, 18%, favoured a full withdrawal from Europe.
The BCC tested five scenarios for the UK's future relationship with the EU. Respondents were asked to give their view on the potential impact of each scenario on Britain's business and economic prospects.
The main focus of business unhappiness was employment law, followed by health and safety law, and regional development polices.
The BCC survey asked respondents to pick from five options:
- Full withdrawal from the EU
- Withdrawal from the EU followed by a trade agreement
- Remain in the EU with specific powers transferred back from Brussels to Westminster
- Remain in EU and integrate further with other EU member states
- Remain in EU with no change to current relationship
The manufacturers' organisation, the EEF, said the government should tread carefully in Europe: "We need to develop a clear long-term vision about what we want the EU to look like in 20 years' time and above all, we need a much better quality debate about the future of the EU.
"The focus of this and future governments should be on working from inside the EU, to ensure it does more to generate growth, jobs and investment with every euro of EU spending being tested against growth. This should be the starting point, not seeking to renegotiate a better deal, however enticing that may seem."
Business' relationship with the EU was last in focus in January when the prime minister called for a referendum.
Some business leaders warned then that David Cameron's EU referendum proposal would hurt investment.
Others backed the prime minister's move.
The BCC's survey, which it calls the EU Business Barometer, is the first major one of British business since the prime minister's policy speech on Europe.
The BCC's director general, John Longworth, said: "Companies believe that re-negotiation, rather than further integration or outright withdrawal, is most likely to deliver business and economic benefit to the UK.
"These findings suggest that UK businesses increasingly feel that some sort of change to Britain's relationship with the EU is needed to boost our trading prospects."
The BCC will test all five scenarios regularly throughout 2013 and 2014 to establish whether businesses' views on the potential economic impacts change over time.