Ewan Brown, chairman of Scottish Financial Enterprise (SFE) and one of Scotland's most senior business figures, said more information was needed.
He said: "A yes vote will bring profound irreversible change to our business environment and it is proper for us to find out as much as we can about what that would mean in practice.
"There is no shortage of hypotheses and assertions, but the fact is nobody knows. The consequences of a yes vote only become clear in the months and years that follow."
Mr Brown, former chairman of Lloyds TSB Scotland and a long-standing director of Stagecoach and of merchant bank Noble Grossart, added: "Ironically we know more about how the other parties to such negotiations would behave than we know about the as yet non-existent entity of a Scottish state."
SFE had consulted over the past year and looked at the evidence, Mr Brown said, in a speech to the body's annual gathering. He said the five big issues were EU membership, currency, financial regulation, a single market for financial services and the transition period after a yes vote.
Mr Brown said: "The introduction of any currency uncertainty constitutes a risk to the large number of daily transactions between Scotland the rest of the UK." Currency was a "pre-requisite for stability", he said, but the conditions were "bound to produce a period of uncertainty ... of a duration not foreseeable".
He added: "Everybody knows the arrangements will have to change but nobody knows what they will be. That presents considerable operational challenges to many companies in many sectors, including our own."
Mr Brown said that, under EU rules, Scotland would become a new regulatory jurisdiction.
He said: "Since financial products and services are tailored to tax, consumer protection and regulatory regimes, any divergence from the rest of the UK would undermine the single market and create uncertainty over the competitive position of Scottish-based providers."
Although EU membership was likely, "the terms of membership or whether the Scottish people would support EU membership on any terms will remain unknown."
Mr Brown said Scotland would need an additional financial regulator costing millions. He said there would also be a period of transition while currency and constitutional arrangements were agreed.
He said: "During this period of uncertainty, business activity and the need to serve customers will continue and standards will need to be maintained if we are not to lose out to the competition."
The chairman said SFE aimed to offer "a well-considered and impartial view on how independence would impact on the financial services industry". Mr Brown concluded: "It would be good if there was much more focus on what is best for Scotland and much less megaphone communication."
A spokesman for Yes Scotland said: "Independence can bring about radical change in the business community - change for the better as a Yes vote is the right way to see Scotland realising our potential and utilising to the full our talent, expertise, business acumen and ambition. We are confident the more information people have, the more likely they are to vote Yes."
A spokesman for the Scottish Government: "It is common sense that Scotland will be part of the EU, just as it is common sense Scotland will keep the pound. The pound is Scotland's currency too and Scotland makes an important contribution to the Sterling Area. For example, Oil & Gas UK estimate North Sea oil and gas boosted UK balance of payments by £32 billion (2012).
"Scotland and the UK have a shared interest in maintaining a common approach to financial stability."