Doctors at rural surgeries on Anglesey are writing to all their patients to ask them to object to plans for two new pharmacies there.
Currently Meddygfa Penybryn in Dwyran and Coed y Glyn in Llanerchymedd provide their own dispensing service.
They warn that the loss of dispensing income could mean losing doctors.
Betsi Cadwaladr University Health Board said Unicare Pharmacy Ltd had submitted 11 applications across for new pharmacies across north Wales.
"We feel strongly that the health board should reject this application but we need our patients support," said Dr ap Ieuan from Penybryn surgery.
He said providing a doctor dispensing service is important in a rural area not only for the convenience of the patients, but it also generates extra income for the practice which subsidises the number of doctors, nurses and other staff.
Around 5,500 items are dispensed at Dwyran per month.
"If the surgery lost the dispensing service we would lose this extra income and this would mean losing members of staff and at least one doctor," Dr ap Ieuan added.
"Losing a doctor would, without doubt, mean that the care we could provide would deteriorate, not only for patients who use the Dwyran surgery, but for the whole of our 8,200 population," he said.
Dr Rhys Griffiths, is the third generation of his family to be associated with the surgery.
"The practice has been serving this community for over 100 years and we want this to continue for another 100 years," he said.
The letter to patients from Coed y Glyn surgery, at Llanerchymedd, tells patients if the application is given the go-ahead the practice would not be allowed to dispense medicines to anyone living within one mile of the proposed pharmacy.
Staff, and one doctor's post, would be put at risk, it said.
"Losing a doctor would inevitably mean a deterioration in the quality of that care, not only for our Llanerchymedd patients, but for the whole of our 6,700 practice population," the letter adds.
Patients have until 30 October to object.
A spokesman for the Betsi Cadwaladr University Health Board said the company has applied for permission to open the Anglesey pharmacies and six in Flintshire, and one in Wrexham, Denbighshire, and Gwynedd.
"There are statutory regulations which determine how these applications are dealt with - particularly in more rural areas, as is often the case in Wales," he said.
"Within the regulations there is a provision, in some instances, which require the health board to consider the issue of potential prejudice to the current provision of pharmaceutical, medical or dispensing services to patients," he added.
As part of the decision making process the board also invites "interested parties" to comment.
The views of professional pharmacists, doctors, local medical committee and Community Pharmacy Wales, and patient representatives are taken into account, he said.
Unicare Pharmacy Ltd, based at Rochdale, Lancashire, has been asked for a comment.