Over two thirds of entrepreneurs here say they are concerned about the impact that Brexit will have on their businesses.
That's according to a new survey which also found that while 60% say they have done some preparation for Brexit, only 17% have done a full analysis and 22% have done nothing to get ready.
The first KPMG Entrepreneurs Barometer also found more than half of those questioned think their company will be impacted if border checks are introduced for goods moving to and from Northern Ireland and the rest of the UK after Brexit.
A similar quantity believe their firms will be hit negatively by currency fluctuations as a consequence of the UK's departure from the EU.
A hard Brexit is bad, but not preparing is just as bad, said Olivia Lynch, Partner at KPMG.
She warned that businesses that don't get ready could face a longer more difficult journey if they don't get their house in order.
Despite the looming threat of Brexit, however, more than two thirds of those entrepreneurs polled expect their turnover will increase over the next 12 months.
41% think their staff levels will also rise, with 57% predicting the number they employ will stay the same.
The study was conducted on KPMG's behalf by RED C Research among key decision makers in a representative sample of 200 "entrepreneurial" firms employing between 10 and 100 employees in the Republic of Ireland between the end of June and middle of July.
The companies were spread across seven sectors and the majority of them were indigenous.
As the focus on climate change increases, the data shows an overwhelming majority of companies support the move towards more action on the issue.
However, more than half are concerned about increases in business costs because of those actions.
On the topic of infrastructure, the survey found that while the majority of respondents have been able to find suitable premises for their business, the cost of renting or leasing a premises or the location of them are significant issues.
Companies based in Dublin are more likely to consider this an issue, and these firms are more likely to face issues due to a lack of public transport and excessive traffic congestion.
40% of those questioned also say staff are finding it difficult to find appropriate residential accommodation and nearly six in every ten say availability of residential accommodation here is a disadvantage for recruitment and retention.
When it comes to the issue of tax, the survey found entrepreneurs tend to be critical of the regime here.
Three quarters think the system is more favorable to multinationals, while more than half feel it puts a significant administrative burden on smaller firms.
There is strong criticism of the R&D tax credit too, with almost half saying it is not working effectively for their business.
The top preference for tax reform in the budget among Irish entrepreneurs are alignment of personal tax rates for self-employed and capital gains tax reform.
Irish entrepreneurs have the highest growth aspirations in Europe but the tax regime is not supporting that growth, said Ms Lynch.