Doctors could be put under pressure when a town surgery with 5,000 patients on its books closes.
Swallowbeck Surgery in North Hykeham will shut its doors at the end of December.
Its doctors Mark and Alison Fallow are retiring after 46 years in the health profession.
NHS Lincolnshire says there are sufficient facilities near to the surgery in Hykeham Road.
But David Baker, a member of the British Medical Association's executive committee in Lincolnshire, says other practices will feel the strain and have to take on more staff.
He said: "The Primary Care Trust had no choice – there was no one that could take over the practice and because it had a house attached to it, the PCT could not take it on itself.
"Some of the patients have built up close relationships with the doctors, so it could be quite stressful and quite difficult.
"Hopefully, the remaining practices will be able to cope with the extra patients but it will be a strain.
"I think they will have to take on extra staff."
The three nearest surgeries are Crossroads Medical Practice in Lincoln Road, Newark Road Surgery and Richmond Medical Centre in Moor Lane.
Patients have been notified of the closure and given details of how to register with other practices.
North Hykeham town councillor Wallace Lee said he was worried elderly patients may be forced to travel further if there was no room at nearby facilities.
"They say the practices will be able to cope, but 5,000 is a lot of people," he said.
"At the Crossroads surgery there is only one full-time doctor and two part-time doctors.
"What will happen if there is no room?
"They may have to go out of Hykeham and that could be an extreme inconvenience.
"For older people and people without a car it's not so easy.
"In the first three months of the year there could be problems, that's my main concern."
Di Pegg, head of contracting for NHS Lincolnshire, said: "All affected patients are being made aware of the planned closure of Swallowbeck Surgery.
"We are working closely with the other practices in the area to ensure that these patients can register with their choice of alternative surgery.
"We are committed to helping local people find an alternative GP practice and wish Drs Mark and Alison Fallon a healthy and happy retirement."
For more information on alternative arrangements and registration, call 01522 782203.
For a full list of alternative practices, visit www.nhs.uk.