Health managers have decided to allow vaping in the grounds of Devon's largest hospital.
Derriford Hospital banned all forms of smoking on its premises from 2016.
But the board of the NHS University Hospitals Plymouth has now rethought the ban, after Public Health England (PHE) said vaping was 95% less harmful than smoking.
The plans would make the hospital "tobacco-free" instead of "smoke-free".
Derriford could also start issuing disposable e-cigarettes as part of its drive to cut levels of smoking.
PHE has said "when supported by a smoking cessation service, [vaping] helped smokers to quit tobacco altogether".
The plans would see the external area at the hospital becoming "vape-friendly" but signage will request people to avoid entrances and bus stops.
'Help smokers quit'
Painted lines and signs "will clearly define the point at which smokers are requested to extinguish their cigarettes" and where they can vape.
Professor John Newton, director of health improvement at PHE, said: "There is no situation where it would be better for your health to continue smoking rather than switching completely to vaping.
"The sooner you stop smoking completely the better.
"We are alert to the risks and the UK has taken a careful approach to maximise the opportunities that e-cigarettes present to help more smokers quit."
PHE has been campaigning since 2018 for the NHS to become truly smoke free.
West Midland NHS Trust banned smoking in hospital grounds, but allowed the use of e-cigarettes outside from last year.