Secondary teachers belonging to the ASTI union have narrowly voted to reject the government's pay proposals.
Under the plans, over 60,000 public servants who are on lower rates of pay since 2011, would receive average increases of more than €3,000.
A total of 58% of members voted with 53% voting to reject the proposals and 47% voting to accept.
Members of the other secondary teachers union, the TUI, already voted to accept the pay plans, while the primary teachers union, the INTO, has rejected them.
The ASTI had previously said the proposals do not go far enough as they do not include back-pay or allowances, and do not achieve equal pay for equal work.
Breda Lynch, President of the ASTI, is welcoming the result.
"I'm very proud as President of the ASTI to see our members stand steadfast
"They feel a strong sense of injustice that we have colleagues on lesser pay and that's what this is about, it's about justice and fairness.
"We didn't give a recommendation because we had committed to working with other unions, without recommendation our members have come out and said no this is not equal pay."
ASTI members have voted to reject the New Entrants’ Salary Measure by 53% to 47%. - https://t.co/6qTtyBUJdO
— ASTI (@astiunion) November 29, 2018
ASTI ballot result on partial pay restoration proposals due today
The result of a ballot of teachers on the Governments partial pay restoration proposals is due today.
The ASTI made no recommendation to its members on how they should vote.
More than 60,000 public servants who have been on lower pay rates since 2011 will get a pay increase of over €3,000 under the Government proposals.
The ASTI has previously said the proposals do not go far enough as they do not include back-pay or allowances, and do not achieve equal pay for equal work.
The Irish National Teachers Organisation has already voted to reject the proposals, while members of the Teachers' Union of Ireland voted to accept them.
The ASTI extended its deadline for postal ballots for members to 5.30pm yesterday evening.
The result is expected at some stage today.