The Irish Medical Organisation is calling on the Government to tackle the shortage of GPs.
Over 600 are due to retire in the coming years, while there is concern that newly qualified doctors will practice abroad.
Pressures in the health service are understood to be deterring GPs from staying on beyond retirement age.
The IMO's Dr Padraig McGarry says the whole country will feel the impact.
He said: "I think it will affect rural practices first because those practices are going to be the ones more difficult to fill.
"This is now spreading into major urban towns and provincial towns and the closure of lists has spread into urban areas.
"I have been in discussion with GPs across the country in the last few weeks and this has reflected as a problem."
- Digital Desk