PricewaterhouseCoopers, KPMG, Ernst & Young and Deloitte have shed one in five Scottish staff in the past two years.
More than 500 fee-earners have left their jobs in Scotland since 2001.
And entrants have also been hit hard; trainee numbers have been slashed by a third.
PwC alone has reduced the number of people it employs in Scotland by 250 since 2001.
It has reduced its Scottish payroll by a quarter and KPMG’s numbers are down by 20%.
The research may be seen as a sign of a weakening Scottish economy.
And the dearth of corporate transactions in the £10m-plus bracket is thought to have hit the big accountancy firms hard.
The research was carried out by CA magazine, the journal of the Institute of Chartered Accountants of Scotland.
Harrison Beale & Owen will (HB&O) have a new chairman and managing director at the helm for 2017
Satvir Bungar promoted to managing director in the mergers and acquisitions team
Carolyn Brown appointed as the first head of client legal services practice RSM Legal
UK senior partner Phil Verity has been elected for a second term at Mazars