The Bull in Harpole stages a pipe smoking competition on Shrove Tuesday every year and the tournament is believed to date back to 1856.
But the introduction of a ban on smoking in public places, due to come into force on July 1, could mean this is the last year the tournament is allowed to take place inside the pub.
Landlord Clive Rimmer, who only took over at the pub last month, said he could be forced to stage the competition in the beer garden in years to come.
He said: "It's something we are going to have to look at. Holding it outside simply wouldn't be the same.
"It takes place on a Tuesday night in February and the beer garden is going to be a bit chilly to say the least.
"It's such a shame because the competition has so much heritage and it looks like it will be wiped out overnight simply because of a new piece of legislation from the Government.
"It will be interesting to see how pubs cope. I think we will be fine as we have a nice garden area, but other pubs might struggle.
"For a lot of people, going to the pub is about having a pint in one hand and a fag in the other. Fifty per cent is suddenly going to be outlawed."
Dozens of people enter the competition every year and regulars hope the competition will continue to be held.
Ben Pentland-Inwood, aged 23, who has been drinking at the pub for four years and now works there as the chef, said: "It adds so much to the atmosphere of a pub to have nights like this. There are so many stories to tell and it's nice in a way to see the tobacco-stained walls, and I say that as a non-smoker. It shows the pub has a history."
This year's competition takes place on Tuesday, February 20, at 7.30pm. To take part can call the pub on Northampton 830666.