Hundreds of pubs and licensed premises in Wales will not be ready when the ban on smoking in public places is introduced in April, it is claimed.
Licensees say the ban has been rushed through by AMs
Many in the trade say the final details being announced only last week means the preparations have been rushed.
The fixed penalties that can be imposed include a £200 fine for premises that do not put up no-smoking signs.
Deputy Health minister John Griffiths said pub landlords have known for four years that the ban was coming.
The final regulations governing the ban were given the rubber stamp by the Welsh Assembly Government last week.
BBC Wales' Eye on Wales programme has found some people feel that the finer details of the ban - due to start in eight weeks - should have been ironed out sooner.
Philip Lay, retail director for Welsh-based brewers SA Brain and Company, said: "I don't think anybody can argue that not having smoke around you is a good thing.
"It's a benefit, but again, a bigger benefit is employment and being able pay your bills at the end of the week.
The assembly government said the ban is four years in coming
"There are a lot of people, particularly the small independent traders, where this is going to put a really serious economic pressure on them and they're very worried because there are going to be pub closures as a result of this."
John Price, secretary of the Licensed Victuallers Association in Wales, runs The Bush Hotel in Blaenclydach, Rhondda.
He said: "They should have compromised as we have asked all along, allow us to have one room smoking and lounge as no smoking. But they won't do it. How it's going to hit us financially, I don't know."
Mr Price said that the rate of smoking in some Welsh pubs means that the ban could affect more than half of their customer base.
He said: "I've got 83% smoking in this pub, they like to come in and have a cigarette and a pint which has been going on for generations.
"I think that everybody thinks it's been pushed forward too quick. They are not giving us time, there will be hundreds of pubs not ready in the Rhondda alone."
But John Griffiths insisted that businesses had known since 2003 that the ban was coming.
He said: "When the opportunity came to have a smoking ban in Wales we were quite clear that we wanted the public health benefit that that ban would bring in place as quickly as possible.
"Whilst I appreciate that until the regulations go through the assembly there isn't certainty as far as what will be allowed in terms of smoking shelters, we've been pretty clear what we propose and that's been on the table since July of last year."
Local authorities will enforce the ban. Fixed penalty notices include £50 for smoking in a smoke-free public place and £200 if a premises fails to display no-smoking signage.
Eye on Wales is broadcast on Radio Wales at 1800 GMT on Monday