New figures show that NHS Borders is spending nearly £2.5m a year on agency locum doctors, a fivefold increase in such spending of nearly £2m since 2009.
In total, NHS Borders has spent more than £5.6m since 2009 on temporary doctors to fill in staffing vacancies.
NHS Boards use locum doctors to cover temporarily over periods of high demand or staff sickness, but they are not seen as a long term solution.
Agency locums tend to cost more than internal NHS locum doctors. The data, collected by the BBC, also shows NHS Borders paid a single agency locum £5,573 for a 48 hour shift.
The news comes after NHS Borders announced it is considering closing local hospitals in Hawick, Duns and Kelso, as part of a cost cutting exercise.
John Lamont, local MSP said: “Clearly locums have their place in providing flexibility in times of demand. However, they are not a cost effective way of staffing hospitals.
“It is concerning that the bill for locums has gone up by nearly £2m in 4 years. This is not only a waste of money, but it means that staff will be increasingly unfamiliar with the hospital they are working in.
“It would be better for patients and better for costs to ensure that staffing is sufficient so as to reduce the need for so many locums. I am sure that NHS Borders will want to look closely at how they can reduce their agency bills.
Due to NHS boards being unable to differentiate between regular medical staff and internal locums, the figure spent on internal locums remains unknown.
NHS spending on locum doctors in Scotland as a whole increased by £18 million compared to last year.