The smoking ban in pubs, bars and restaurants in Wales came into effect this morning at 6am.
The Welsh Assembly has started an advertising campaign to warn people that the Welsh ban has started before the English one and that they could be liable for a £50 fine if caught smoking in public places.
Licensed Victuallers Association Wales secretary John Price claimed many long-serving licensees have become so disillusioned that they are leaving the trade.
"A lot of hosts who have been in the trade for 20 years or so are selling up now because of this ban," he said.
"There is no money to be made - it will be terrible."They won't stand outside by the main road to have a smoke - they'll stay at home.John Price, Licensed Victuallers Association Wales secretary
Price, who also runs the Bush Hotel in Blaenclydach, Rhondda, said: "More than 80% of my customers smoke - they are ex-miners who have smoked all their lives. They won't stand outside by the main road to have a smoke - they'll stay at home."
Price hit out at the rushed legislation, with guidance notes issued just 10 weeks before implementation.
"We have not been given enough time to prepare. There will be huge problems. A lot of pubs will close."I don't think my trade will be affected - it's not as big a deal as some make out.Nick Otley of the Bunch of Grapes in Ponty-pridd
Stephen Bale of the Caledonia Inn in Pembroke Dock, Pembrokeshire said: "I've done all I can to prepare - so fingers crossed that trade holds up. If we suffered a 25% dip in trade we'd lose our business. We have already lost one woman from our darts team as she won't be allowed to smoke. If we lost our darts team that would be another £200 gone every other Tuesday."
But Nick Otley of the Bunch of Grapes in Ponty-pridd, Mid Glamorgan, said: "Bring it on. We have been 75% no-smoking for a while. I don't think my trade will be affected - it's not as big a deal as some make out."
SA Brain retail director Philip Lay said he expects an initial drop in trade.
"We're as ready as we can be. Reports from Scotland and Ireland suggest there will be initial pain, but if you're prepared, you can weather the storm. If you bury your head in the sand, you'll struggle."