The Irish Nurses and Midwives Organisation has made a demand for full reversal of all pay cuts and the pension levy.
In a statement issued late last night, the INMO warned that it would also be seeking a return to the 37-hour working week, which was increased to 39 hours in the Haddington Road Agreement.
INMO Director of Industrial Relations Phil Ni Sheadhgha said it was "payback time".
She said that the union would be seeking restoration of all pay cuts, abolition of the pension levy, a 37-hour working week, and safe staffing levels in clinical areas.
Talks between the government and public service unions on a successor to the Haddington Road Agreement are expected to get under way before the summer.
However, the INMO is the first union to set out its demands in public.
The union says that with the economy recovering, and "substantial" pay improvements evident in industry across the country, it expects the outcome of those talks to see a return to salaries in 2009, when the first of a series of pay cuts was implemented.
The union will today issue a briefing document to all members, and will hold regional consultation meetings with members with a view to finalising the union's position at talks with the Government later this year.
Observers expect the public service pay restoration talks to get under way in the early summer after the union conference season has concluded.
It is thought they must conclude by the end of September, so that the Government will be able to include a forecast for the 2016 public pay bill in the October budget.
However, sources believe it is unlikely that the government will be willing to restore any of the 15 million unpaid additional hours secured in the Haddington Road Agreement.