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.
Brian Burke, business development director, has moved within the firm to 'develop Quantuma’s networks with Sussex professional firms'
Stephen Mills joins the Manchester office from IBM, where he spent 12 years as an associate partner in the data, analytics and cognitive consulting group
Rupert Guppy will be responsible for capital allowances in the southern region, and joins the firm from specialist consultancy E3 Consulting
Richard Lewis has been appointed to the firm's restructuring and recovery services team