Around 1,720 doctors from the European Economic Area (EEA) responded to the survey, nearly 15 per cent of the 12,000 now working in the NHS, with almost half of these (45 per cent) saying they are considering leaving.
There are now about 12,000 EEA doctors in the NHS, which constitutes 7.7% of the United Kingdom medical workforce.
In the UK-wide survey of more than 1,700 doctors who gained their primary qualification in another European country, the British Medical Association (BMA) found that nearly half (45 per cent) were considering leaving the United Kingdom following its exit from the EU, while 19 per cent had already arranged to move elsewhere for work.
"It's also vital that any future immigration system is flexible enough to ensure the NHS can recruit and retain doctors and other NHS workers in sufficient numbers".
"Our NHS and patient care are all the richer for having a diverse workforce - it's crucial we don't lose valuable experience and expertise because of Brexit".
Of the EEA doctors questioned for the survey, 45% said they were considering leaving the United Kingdom, with a further 29% saying they were not sure whether they would leave or not.
Danny Mortimer, co-convener of the Cavendish Coalition - a group seeking to support the post-Brexit staffing needs of the UK's health and social care system - said European Union citizens already living and working in the United Kingdom must be given firm assurances of their status.
The BMA's treasurer, Dr Andrew Dearden said: "That so many European Union doctors are actively planning to leave the United Kingdom is a cause for real concern".
The Department of Health criticised the findings, saying there were more EEA nationals on the United Kingdom medical register this year than at the time of the Brexit vote - 21,609 compared to 21,539 as in June 2016.
'Many have dedicated years of service to the NHS and medical research in the United Kingdom, and without them our health service would not be able to cope.
77% of those surveyed by the BMA said they would be more likely to leave the United Kingdom if there was a negative outcome in Brexit negotiations over citizens' rights.
The countries most likely to benefit from the exodus of NHS medical professionals were Germany, Spain and Australia. "In fact, there are actually more European Union doctors working in the NHS since the European Union referendum, more European Union graduates joining the United Kingdom medical register and 3,193 more European Union nationals working in the NHS overall".
Dr Nardini, who moved back to Italy in August after almost two years in Manchester and Teesside, said Brexit had been a "key factor".
He added: "One of my main concerns was around whether my qualifications would continue to be recognised overseas and in the UK".
"There's so much uncertainty at the moment - moving back to Italy and completing my training here seemed like the safer option". "Failure to do so seriously risks increasing staff shortages and exacerbating the already dire crisis in our health and care system".