Members of the Association of Secondary Teachers in Ireland (ASTI) have voted overwhelmingly to withdraw from working 'Croke Park' hours.
The unions members voted 68.5% to 31.5% and say the hours are highly prescriptive and unproductive.
The current hours were introduced under the Haddington Road Agreement, and see teachers working for an additional 33 hours a year.
The ASTI says today's ballot result is a 'very strong statement' from the members to the Government after years of cuts and reduced resources.
In a statement, ASTI President Máire G Ní Chiarba said: “What teachers are saying is that they want to be able to get on with their jobs, instead of having to waste time completing bureaucratic box-ticking exercises.
"The Croke Park hours divert teachers’ time away from core duties such as teaching, learning, and building relations with their students," she added.
The ASTI Standing Committee will meet tomorrow to consider the outcome of the ballot, which had a 76% turnout.