Almost a quarter of Scotland's chairs may be purged by Scottish health minister Susan Deacon in a bid to 'refresh' the service.
Ms Deacon is calling for the chair of every trust and health board in Scotland to attend a personal meeting to discuss their future.
There is widespread speculation that about 10 of the 43 individuals involved will lose their posts.
At the first annual conference of the Institute of Healthcare Management in Scotland last week, Ms Deacon told delegates: 'People want and need to see their NHS improving. We need people who make things happen - rather than people that things happen to.
'Those who share my desire to accelerate the process of change and improve services in local communities have nothing to fear - and much to gain.'
Two chairs are facing widespread media speculation that they will lose their jobs: Frances Havenga, chair of Tayside health board, and Sir William Stewart, chair of Tayside University Hospitals trust.
Tayside has been battling with long running financial problems, but Ms Havenga said she felt it delivered 'highest-quality health services'. She added:
'I am as committed as ever to ensuring that we continue to deliver healthcare in a way which makes a real and positive difference to people's lives.
'I am aware that a briefing given by the members of the Executive has given rise to speculation about my position, but I stress that I have heard nothing from the Executive on this matter.'
Sir William has already been named as the successor in September to Princess Anne as president of the British Association for the Advancement of Science. He said he knew nothing about his position, 'except what I read in the papers'.
One NHS insider, who did not wish to be named, said: 'Everyone has known for some time that there would be a purge.
'I do think that at least six will go and they seem to be selecting them on the basis of who is on message.
'It is true that some of these people are the dinosaurs of the service and probably would have gone anyway.
'But this sort of move appeals to the centrist views of this government.'
But Wai-Yin Hatton, chair of the Scottish division of the Institute of Healthcare Management and chief executive of Ayrshire and Arran health board, said: 'It is only to be expected that Susan Deacon would be reviewing all trust and board chair positions at this time.'
She hoped Ms Deacon would use the opportunity to increase the number of women chairs.
And Pat Dawson, director of the Scottish Association of Health Councils, said: 'The government appoints these people to push through its policies.
'In an agenda which aims to put patients at the centre of the NHS I think that we do need strong leadership and management, so we would welcome changes which brought about a more effective, cohesive delivery of the service.'
Margaret Ford, chair of Lothian health board, who has been on secondment to the Scottish Executive for six months, is expected to play a major role in the new modernisation forum which Ms Deacon is establishing to look at ways of improving the operation of the service.
Ms Deacon is a former employee of Mrs Ford at her Eglinton Management Consultancy in Edinburgh.
But talk of cronyism was dismissed by one NHS insider who said: 'Margaret is a star. Most people in the service would select Margaret as someone to lead the way as she is so good at her job.'