The Royal College of GPs said its findings were fresh evidence that the status of European Union doctors working in the UK must be protected.
In Northern Ireland, EU doctors are 11% of the workforce while in England 5% of GPs are from the EU.
The college claimed opinion poll backing for its argument.
The YouGov poll found that 56% of people backed continued immigration of doctors into the UK to work as GPs.
And 59% backed the idea that next government should immediately guarantee the status of existing EU GPs in the UK.
The college estimates that some 2,137 GPs across the UK are from other EU countries.
College chair Professor Helen Stokes-Lampard said: “We desperately need thousands more GPs right across the UK, and in England we have been promised 5,000 more by 2020 – but these figures indicate that we risk losing well over 2,000 family doctors from the NHS if their position is not secured as part of Brexit negotiations, and that is just not safe or acceptable.”