An organisation representing Scottish pubs and hotels has claimed the smoking ban has driven away regular drinkers.
The SLTA warned the smoking ban would hit the pub trade
The Scottish Licensed Trade Association surveyed 365 members and said sales of alcohol appeared to have fallen by more than 10% since the ban was introduced.
Paul Waterson, the chief executive of the SLTA, said the effects of the ban were "bad enough" at the moment and there would be "worse to come".
However, many pubs and hotels have spoken out in favour of the ban.
They say a large number of SLTA members did not reply to the survey.
Smoking was banned in enclosed public places in Scotland, including pubs and restaurants, on 26 March.
The SLTA has been an outspoken critic of the ban and has warned it would have major implications for the pub trade.
The findings of the organisation's survey were published in Edinburgh on Wednesday morning.
It said 46% of licensees reported a drop in visits by regulars since the ban came into effect on 26 March, while only 5% reported an increase.
The impact on sales was said to be similar, with 51% reporting that regulars were spending less and only 7% more.
Mr Waterson, owner of the Flagship Hotel group, said: "We were told that business would improve as a result of the ban, something we never believed.
"Now even our prediction of 7% loss of business has proved optimistic.
"Drink sales look to have dropped by over 10% and surprisingly even food sales are down 3%."
The SLTA survey said losses had not been counter-balanced by new business from non-smokers, with 20% reporting more new customers or more frequent visits but 17% reporting fewer.
Mr Waterson said: "This ban will put some hard-working licensees out of business and many bar staff out of jobs."
It was difficult to tell whether any pubs would be forced to close because the ban was only months old, he told BBC Radio's Good Morning Scotland programme.
"We are convinced we will not see the real impact of the ban until the winter months."
He said: "Quite a lot of publicans are taking the view that the ban is here and they have to make it work as best they can."
Mr Waterson warned that worse was to come.
He said: "Figures from the Scottish Executive say that there has been 99% compliance, which is extraordinary, and that has happened because we have been positive.
"We tried to educate customers, staff and indeed licensees before the ban came in and that has been successful.
"We have the ban and we tried to implement the ban. But this is about the business effects on our membership.
"We believe there is worse to come and it is bad enough at the moment."
Mr Waterson said the survey showed the effect of the ban varied with the facilities on offer.
Landlocked pubs with no outdoor areas suffered most as customers either stayed at home or went elsewhere.
Sixty-four per cent of them reported a drop in business - and only 4% an increase.
But outlets with good smoking facilities had done well, or at least held their own.
The smoking ban has been in effect for nearly five months
Lynn Adams, of the George Bar in Hamilton, Lanarkshire, said: "I think on the whole things could be a lot worse for me in my pub.
"My outdoor area has helped a lot and trade is ticking over but, as my smoking customers say, what happens when winter arrives?
"This is when we will really feel it."
Health Minister Andy Kerr said he had not met one person who wanted to turn the clock back on the ban.
He added: "While it is too early to say precisely what the impact in Scotland is, there is no evidence to suggest that pubs, cafes or restaurants will go out of business as a direct result of the smoking ban coming into effect.
"Data from New York, where the ban has been in place for over two years, shows that in this sector, takings were up, employment was up, openings were up and the number of liquor licenses also increased.
"Seven out of 10 people don't smoke and of those who do, seven out of 10 want to give up.
"This presents huge marketing opportunities for the hospitality sector. People do not go out just to smoke and drink, but to socialise with friends and colleagues."