The number of heads being forced out of their jobs has increased five-fold in the past four years under intense political pressure on school leaders to deliver results.
About 150 secondary heads and deputies were made to leave their positions last year - up from just 30 in 200405 - according to new figures from the Association of School and College Leaders.
The expansion of academies and the introduction of the National Challenge scheme, targeted at schools with low exam results, account for about 75 of the job losses, the association said.
In other cases, senior staff have been forced out following concerns about their performance raised by local authorities or in Ofsted inspections, the association added.
The rapid increase has raised serious concerns that heads and senior school leaders are the victims of unrealistic expectations to deliver results too quickly.
There is concern that numbers may continue to rise as the Government's attention turns to coasting schools and extends the challenge scheme to primaries.
John Dunford, ASCL general secretary, said: "Taking on headship in a challenging school can be a big career risk.
"Local authorities are under pressure from the Government to show that they are improving their schools and too often they believe that is best demonstrated by sacking heads.
"In the case of academies, sponsors want to appoint their own teacher, even when current heads are improving their schools."
Dr Dunford, who will be raising the problem at the ASCL annual conference next week, said school leaders were sacked because of the misuse of school data and an emphasis on raw exam results.
He was alarmed that the axe was falling on young heads, who were given inadequate support. "Too often headteachers are not given time and space to turn around what may have been a decade of underperformance," he said.
One young headteacher with a track record of turning around failing schools, who was made to leave his job last year, said: "It is devastating because I'm still in a position where I feel I have an awful lot to contribute. I suspect in the short-term that getting back into headship will be very difficult."
The head, who chose not to be named, added: "The reasons that schools are in challenging situations are complex and fixing that in a short space of time is almost asking the impossible. The removal of heads who face difficulties can be ruthless."
The majority of forced-out school leaders sign compromise agreements, which means they receive a pay-off. ASCL members received more than Pounds 4.3 million in compensation in the past year, with the highest single payment totalling Pounds 100,000.
Mick Brookes, general secretary of the National Association of Head Teachers, said that jobs in primaries were also becoming increasingly fragile.
"The coasting schools list is now up and running and those heads, often unfairly accused of complacency, are finding their positions being challenged," he said.
The concerns come as the country faces a potential leadership crisis, with half of current heads expected to retire by 2012.
A spokeswoman for the Department for Children, Schools and Families said: "We have no evidence that high-quality school leaders are being lost to the profession."
National Challenge resources are being used to improve leadership teams in schools with low results, she added.
Leader, page 2
By the numbers
150 Secondary school leaders forced out last year.
30 Secondary school leaders forced out in 200405.
Pounds 4.3million Amount paid in compensation to heads last year.
Pounds 100,000 Highest single payout.
50 per cent Proportion of heads expected to retire by 2012.