100 people die from smoking every week in Ireland, according to the HSE.
The health service has published research on what is World No Tobacco Day, which finds 1 in 4 men and 1 in 5 women still smoke, while it is most common among young people.
There are now more quitters than smokers here.
But Dr Paul Kavanagh, who is a consultant in public health medicine and the HSE's lead expert on tobacco, says more needs to be done.
"Despite that progress, what our research highlights is that there are a number of groups being left behind.
"They would include male smokers, people in lower socio-economic groups and people with mental health problems.
"It is very important we focus on those to ensure that everyone benefits from the progress we are making in tobacco control."
- Digital Desk