Sunand Prasad (pictured), Les Sparks and Nicholas Serota have all stepped down from the board of commissioners.
All three were at the top of the organisation when it formed, and have pushed it forward.
It will be seen as the end of an era in the organisation, a feeling that will be reinforced when Paul Finch steps down in the middle of next year.
The trio will be replaced by Joyce Bridges, a planner; M J Long, a highly regarded architect; and Lorna Walker, an environmental engineer.
'It is no exaggeration to say that CABE would not be as effective and influential as it is today without the contribution of Les Sparks, Sir Nicholas Serota and Sunand Prasad,' John Sorrell said some months ago.
'Their work and guidance has been invaluable,' he added.
Deyan Sudjic, the writer and Design Museum director, will take over from Paul Finch when he finally leaves.