Just under half of Northern Ireland companies are already feeling a negative impact from Brexit and only 30% can identify opportunities from it, according to a survey.
Belfast-based corporate law firm Carson McDowell said its research into company bosses' Brexit attitudes showed that around 70% could not yet identify any opportunities arising from it.
But the remainder (31%) said they were optimistic over the prospects for "reduced red tape, access to new markets and greater input to legislative processes".
However, just under half (49%) of the 101 business leaders surveyed said their firms had been negatively impacted by the Brexit decision already.
Only 12% said they had experienced a positive change while one-third of respondents said there had been no noticeable difference.
Over half said they would be hit by any change to the present border arrangements on the island - and just under half said they would be harmed by the arrival of a trade border between Northern Ireland and Great Britain.
But the majority were also already contingency planning for the effect of Brexit after March next year.
Around one-third had sought professional advice before doing so.
Michael Johnston, managing partner at Carson McDowell, said: "Whilst it is encouraging to see that most businesses have started to prepare for Brexit, the lack of clarity is hampering how they are able to do so in a constructive and meaningful way.
"In the next 11 months the government will need to provide a level of detail and support that will allow local businesses to manage the risks and actively identify opportunities that may come in the post-Brexit environment.
"We recommend that businesses proceed with contingency planning and seek relevant professional advice in order to prepare for all possible outcomes."
The survey was carried out by Survey Monkey.