The air and land ambulance were called this morning to help the man after he had a heart attack.
The man, thought to be in his 60s or 70s, was at Oasis Dental Care on Market Place.
Paramedics restarted the man's heart at the scene and a defibrillator that was on site was used.
The air ambulance landed at 10.20am on the lawn at Paston Sixth Form College's Griffons site.
After treating him at the scene, he was then taken to the helicopter at 11.30am on a stretcher wearing a breathing mask and heart monitor.
Caretaker at the college, Steve Nicholls, said: 'We heard the air ambulance coming and ran across just to do whatever we could. We took down temporary fencing so the medical team could bring the patient across.
'If the incident had happened tomorrow there would not have been anyone on site.'
A spokesperson from Oasis Dental Care said: 'We can confirm that while waiting for an appointment earlier today, a patient was taken ill in the waiting room of our Oasis Dental Care practice in North Walsham.
'Medically trained staff from the practice immediately responded, administering crucial first aid and quickly alerted the emergency services who promptly arrived at the scene to then attend to the patient further.'
The air ambulance took off at 11.40am to take the man to the Norfolk and Norwich University Hospital for further treatment.
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