Members of The Garda Representative Association (GRA) have voted against changes to the proposed Working Time Agreement, including a new roster.
A total of 5,541 members voted, representing a 55% turnout.
Some 31.2% of members voted for the ballot, and 68.8% of members voted against.
The proposed changes had sought to bring improvements and a better work-life balance.
They had been endorsed by the GRA Central Executive Committee, with a recommendation to the membership that it be approved.
President of the GRA, Dermot O'Brien, said: "The proposed WTA and revised roster changes were based on the issues identified by our members".
"The Garda Representative Association and the Central Executive Committee is a democratic organisation based on democratic decisions made by its members".
"We will now take this result on board and look at next steps. The number one priority of the Garda Representative Association is pay restoration and pay increases for our members".
The GRA represents more than 10,500 rank and file members of An Garda Síochána.