The trade is bracing itself for the opening of a rash of new Amsterdam-style cannabis cafés, after experts recommended a change in the law surrounding the drug's use.
The government's drugs advisory committee has recommended reclassifying cannabis from a Class B drug to a Class C drug - which would mean reduced penalties for possession.
And so confident are campaigners that downgrading cannabis is inevitable, that they are setting up cafés ahead of the law being changed.
Trade leaders fear that, while this may not directly hit trade in pubs, it could lead to problems regarding penalties for licensees allowing the drug to be smoked on their premises. There is also concern about the dangers of mixing the drug with alcohol.
As the law stands, licensees who allow cannabis on their premises risk losing their licence, but reclassifying the drug is likely to make it more difficult for licensees to keep it off their premises.
Tony Payne, chief executive of the Federation of Licensed Victuallers Associations, said he had asked the government for a meeting to discuss the issue.
"I think mixing cannabis and alcohol is dangerous," he said. "But if cannabis is legalised individual licensees would decide whether to allow the drug and compete with the cafés."
Britain's first cannabis coffee shop, the Dutch Experience in Stockport, attracts about 200 customers every day - despite being raided by the police three times since it opened last year.
Dutch Experience 2 is due to open its doors in Bournemouth in the next couple of weeks and reports suggest other coffee shops are planned in Lambeth and Hoxton in London, as well as Edinburgh, Glasgow, Liverpool, Brighton, Anglesey and Milton Keynes.
In the meantime, licensees have been warned that cannabis is still illegal and advised to take appropriate steps if customers are found with the drug.