GWENT could face an exodus of more than 1,500 teachers as one in three look set to quit the classroom within five years.
Overwork, badly behaved pupils, red tape, and government interference are being blamed for driving down morale.
A survey of teachers in England by the General Teaching Council shows one in three do not expect to be teaching in five years' time.
And the National Union of Teachers in Wales says working conditions are similar enough for teachers in Greater Gwent to feel the same way.
That could mean a loss of 1,536: 359 of Newport's 1,077 teachers, 219 quitting in Monmouthshire, 207 in Blaenau Gwent, 257 in Torfaen and 494 in Caerphilly. Rhys Williams, campaigns officer at the NUT, said: "Problems with overwork and pupil behaviour certainly apply in Wales and need to be addressed.
"The extent of the demoralisation is a new development and it's very sad that so many people are going into teaching fired up and are then losing that enthusiasm.
"There was a time when if you were young, imaginative and had initiative, then teaching was appropriate. The feeling now is if you have those skills you are not going to fit into the straitjacket of teaching and its set curriculums."
He said education in Wales enjoyed stronger support from its local authorities than in England, and that may help Wales tackle the problems more effectively. The report also reflected the immense satisfaction many get from teaching.
And it showed that half of the one in three set to leave the job were due to retire. But that still means 768 could be set to leave.
Monmouthshire councillor Graham Down, a primary-school governor, said: "Recruitment isn't the problem, it's keeping them there once they see life in the job. "Since 1997 schools have been snowed under with unnecessary paperwork, gimmicky initiatives and arbitrary targets."
Yet a spokesman for the General Teaching Council for Wales said teacher retention was not a major issue in Wales.
He said there were many teachers coming into the profession and that shortages only lay in the secondary-school subjects of science, maths and Welsh.
An Assembly spokesman said they were taking steps to reduce teacher workload. On Wednesday, Education Minister Jane Davidson signed a national agreement with school workforce unions to tackle teacher workload and raise standards.
The agreement means the teachers' contract will be changed to significantly reduce their workload and so provide more time for preparing and planning lessons. Ms Davidson said: "Tired teachers are not effective teachers, and a long-hours culture is not conducive to raising standards."
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