Increasing the age for the sale of tobacco to 21 could see smoking rates drop by up to 34%.
That's according to the Irish Heart Foundation, which conducted a poll and found that almost three-quarters of people would be in favour of the change.
The Ipsos-MRBI poll found that 73% are in favour of raising the age, with 26% disagreeing and 1% undecided.
In the 18 to 24 age group, 71% backed the proposal. The poll saw 1,029 people aged over 15 surveyed by phone.
The charity - which also wants the change to extend to e-cigarettes - says data showing an increase in teenage smoking strengthens the case for a tobacco ban for under-21s.
In 1995, the teen smoking rate in Ireland was 41% - which fell dramatically to 13.1% by 2015.
However by 2019, this percentage had increased back up to 14.4%.
Chris Macey, director of advocacy at the Irish Heart Foundation, says such a move could have a major impact.
"It passes the three key tests really, as we would see it. Firstly is it proportionate - yes, will be it effective - yes.
"Tobacco 21 laws in the United States have reduced smoking rates among 18 to 20 year olds by up to 34%.
"We would be confident similar laws will work in Ireland, due to the hugely positive impact of increasing the age of sale here in 2002 from 16 to 18.
"And the third one is would it breach young people's rights - and we would say no to that."
Mr Macey says that those under-21 are already prohibited from certain activities such as adopting children, driving large passenger vehicles and standing in national and European elections.
He says: "The smoking rate fell dramatically over the last 25 years, from 41% to 13%.
"It's started rising again - we're concerned it's down to the impact that e-cigarettes have had".
He adds: "The evidence strongly suggests that raising the age of sale will turn the tide back in the right direction, disrupting a high rate of smokers moving from casual use to addiction between the ages of 18 and 20.
"The US Institute of Medicine says 223,000 lives will be saved among those born between 2000 to 2019".
