The health service in Tayside and Fife spent more than £10.5 million covering consultant vacancies in its hospitals last year.
The figure is an increase of 86% on the previous year as health boards have been forced to bring in more locums as they struggle to fill consultant posts.
The British Medical Association (BMA) has said the issue is putting significant pressure on doctors left to cover the gaps.
Health services and the public purse are also being stretched as waiting times increase due to staff shortages and more is spent on locums.
The BMA added the current shortage was worse than suggested by Scottish Government figures, which do not include posts waiting to be advertised.
Health Secretary Shona Robison has acknowledged the NHS in Scotland faces “significant challenges” in tackling the number of consultant vacancies in hospitals and has pledged to work with the BMA to find a solution.
Serious concern has been expressed at the amount being spent on agency locum doctors in particular.
Last year, NHS Tayside paid almost £2.4m on agency doctors an increase of more than 1,000% on 2012-13.
NHS Fife spent a total of almost £6m during the same period, up 56% on the previous year.
Mid Scotland and Fife Conservative MSP Liz Smith said the figures suggested something was radically wrong in the recruitment of doctors, while Labour’s spokesman, Richard Simpson, said health boards were at breaking point and the use of locum consultants was becoming the norm.
Dr Nikki Thompson, from the BMA, said: “The reality on the ground does not tally with the official vacancy figures and the information provided by health boards backs that up. We are not suggesting the official figures are inaccurate, but they don’t show the whole picture.”