Addenbrooke's Hospital in Cambridge has implemented a total smoking ban to encourage healthier lifestyles.
Staff, visitors and patients won't be able to smoke anywhere on site - and there's no longer any outdoor smoking areas.
It also applies to the Rosie Maternity Hospital.
The Trust's Chief Executive Dr Keith McNeil says it's in accordance with national guidelines that hospitals should be smoke free.
"It sends a message that we're not just about treating people here, we want society as a whole to be healthier," he said.
"It's very important from that point of view that we don't condone smoking on the site anywhere."
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Sunday forecast: Heavy rain is expected for a time with gusty winds, then clearing during the afternoon.
March in the Anglia region has been much drier and sunnier than normal although temperatures have been around average.
Breezy and rather cloudy overnight but mainly dry. On Sunday, becoming wet and windy for much of the morning after a dry start.