The Licensed Victuallers Association (LVA) Wales is fighting back against a new rate relief scheme which it claims will hit rural pubs hard.
John Price, the LVA's secretary, said that pubs have been hit with a "double whammy" with the smoking ban and the change in rate relief.
The LVA is currently collating figures to present to the Welsh Assembly to show that licensees have lost out under the new rate relief scheme - which came into effect on April 1 - a day before the smoking ban came into force.
Under the old Rural Rate Relief Scheme all pubs in towns with a population of less than 3,000 were offered a 50 per cent discount.
But under the new Small Business Rate Relief Scheme only those with a rateable value less than £2,000 will receive 50 per cent rate relief, while those with a value between £2,001 and £5,000 will get just 25 per cent relief.
The LVA argues that this bars all but Wales' very smallest rural pubs from significant rate relief.
Mr Price claims that the rates bill at his own pub, the Bush Hotel in Blaenclydach, South Walesl will go up by £800.
Former licensee Peter Flower, who is calculating for the LVA how much pubs will lose out , estimates that 35 per cent of pubs will be affected.
"This could be the final straw for some of these pubs," he said.
Meanwhile, in the first week of the smoking ban, Mr Price said his trade was down 37 per cent. "It's terrible. A lot of elderly people have stopped coming because they don't want to go outside to smoke," he said.
However, Andy Melbourne, licensee at the Rummer Tavern, in Cardiff said it was far too early to gauge the effect of the ban. "We can't tell at the moment, it's only been a week. Any information now is totally irrelevant."