More than one in 10 people will still be smoking in 2034 despite a Scottish government commitment to stub out the habit by then, health campaigners say.
Ministers have set a goal of creating a "tobacco-free generation", with 5% or less of the population smoking in 14 years' time.
However, Cancer Research UK has warned that deadline could be missed by up to 16 years in the poorest communities.
The Scottish government said smoking in Scotland "continues to fall".
Cancer Research UK analysis suggested 12% of adults could still be smokers by 2034 if smoking rates decline as expected.
To achieve the 2034 target, the charity said smoking rates would have to drop almost twice as fast - with smokers needing to fall by 585,000 from the current total.
Meanwhile, in the poorest communities more than 10% of people could still be smoking by 2050, the analysis suggested.
It comes after the number of smokers increased for the first time in seven years, rising from 806,817 in 2017-18 to 808,829 in 2018-19.
Help to quit
While statistics for 2018 showed 19% of all adults still light up, the smoking rate in the most deprived parts of Scotland was almost a third at 32%.
To help reach the 2034 target, the charity has called for more action from the government, suggesting all smokers who visit hospital should routinely be offered help to quit.
Marion O'Neill, Cancer Research UK's head of external affairs in Scotland, said: "Smoking has a catastrophic impact on health. It's enormously addictive and difficult to quit so more needs to be done to ensure people know about the support available to give up."
Smoking remains the biggest preventable cause of cancer in Scotland, with 4,100 people dying from lung cancer every year.
The Scottish government welcomed the Cancer Research UK recommendations which, it said, "endorses many of our current plans".
A spokesman added: "Smoking prevalence in Scotland continues to fall and we remain determined to create a tobacco-free generation by 2034.
"Attitudes to smoking are clearly changing but we will leave no stone unturned in cessation and prevention."