People who smoke because they are stressed are less likely to be able to quit than other smokers.
Researchers found smokers wrongly think cigarettes will help relieve stress.
In fact, smoking exacerbates stressful feelings, experts told the British Psychological Society conference in Stoke-on Trent.
They said counsellors helping smokers quit should tackle the causes of stress and offer other ways of coping with problems.
Trigger
Researchers from Hillingdon Hospital in north-west London followed 550 smokers on a seven week cessation programme.
The smokers received a combination of nicotine replacement therapy and group counselling.
People were then followed up four weeks after the programme ended to see if they had successfully quit smoking.
Dr Christina Chryssanthopoulou, who led the study, told BBC News Online: "We found that those people who used smoking as a way of dealing with stress were not as successful at stopping as people who didn't."
She added: "Stress is one of the most important reasons people smoke.
"Most smokers report that even when they give up successfully, one of the most important causes of relapse is stress."
Causes
Dr Chryssanthopoulou said nicotine could actually exacerbate stressful feelings.
"People feel stressed, then they smoke, but the nicotine makes them feel stressed - it's a vicious circle.
"Health staff need to provide more information about what nicotine does and the relationship between nicotine and stress.
"We need to look at ways of providing alternative methods of coping with stress to smokers."
Dr Amanda Sandford of the charity Action on Smoking and Health said: "Smokers think that smoking is helping them to relieve their stress, whereas actually it's having the opposite effect.
"People are fooling themselves if they think carrying on smoking is going to help.
"For the professionals who are counselling smokers, it might be a case of finding out the causes of the stress and dealing with those."