New figures show 218 positions are unfilled and almost one-quarter have lain empty for half a year or more.
Scottish Tory health spokesman Jackson Carlaw highlighted the figures and said the time it was taking to recruit senior doctors should be ringing alarm bells.
Mr Carlaw said: "These are highly skilled individuals who can make the world of difference to the outcome for numerous patients. The Scottish Government needs to explain why these vacancies have sat empty for so long, and what it intends to do about the situation, which seems to be reaching crisis level in some parts."
NHS Grampian appears to be particularly affected. Out of the 52 vacancies which have existed for six months or more, 19 are in the Grampian region.
In total, the figures for December 2013 show 4.5% of positions were vacant, down on last summer when the rate hit a six-year high of 4.7% but above the figure for December 2012 of 3.2%.
The number of staff working across the NHS has risen by more than 5% in six years, according to the Scottish Government. The consultant workforce employed by the service has also grown some 2.3% during this time.
Some specialist fields, including emergency and acute medicine are particularly short of senior doctors.
Mr Carlaw said: "While we need more nurses on wards, it's also crucial we have enough staff operating at all levels if our NHS is to be a truly first-class service.
"What chance is there of it being a robust, 24/7 outfit if dozens of consultant posts are vacant for months on end?"