The smoking ban in Guernsey is likely to have a negative impact on takings, landlords have been warned by their Scottish counterparts.
Some smokers may not want to stand outside pubs in the winter
A survey by the Scottish Licensed Trade Association (SLTA) indicated a fall in sales since the ban in March.
It is a mirror of what happened in Ireland and the association has warned Guernsey is unlikely to be different.
But only 365 members responded to the survey and many of Scotland's 15,000 pubs and restaurants support the ban.
The members who did complete the survey said sales of alcohol have dropped by more than 10% .
Paul Waterson, the chief executive of the SLTA has warned it is the tills in Guernsey's more traditional pubs away from the main tourist areas which are likely to be affected.
He told BBC News: "It's the pubs who have no facilities for smokers and that's more often the traditional-type of pub.
"Maybe with a lot of hard work and in time things will bottom out, but we're suggesting ther are are going to be some casualties in Guernsey and some places might have to close.
"What I want to say to landlords in Guernsey is that they've got to prepare as much as possible and maybe put more money into an outside area."
Mr Waterson said he had no grounds for optimism in the run up to winter, with the likelihood of fewer people being prepared to smoke outside.