Tens of thousands of NHS workers will take industrial action and other forms of protest next month in the continuing bitter row over pensions.
Unite said its 100,000 health service members will walk out on May 10, a day after the Queen's Speech, which is expected to include a Parliamentary Bill on the Government's controversial reforms.
Other workers are expected to join the strike and there could be further industrial action in June.
Unite said its NHS members, including health visitors, pharmacists and paramedics, face paying an average of £30 a month more for their pensions.
The dispute has been raging for well over a year and sparked a strike by more than 1.5 million public sector workers last November.
Unite said it expected other public sector unions to join the May 10 action as part of the continuing campaign of opposition to the Government's changes.
Officials pointed out that the pension reforms came against a backdrop of pay freezes and cuts in the public sector, and the prospect of regional pay being introduced.
National officer Rachael Maskell said: "The Government is picking the pockets of health workers by an average of £30 a month in order to pay for pension changes which will see people having to work longer to get less.
"This disgraceful attack comes against a backdrop of pay freezes and the threat of regional pay in the public sector. In the face of continued attacks, health workers will be stepping up their campaign and looking to join other public sector workers in taking action on May 10."
Unite's health members voted by more than 9-1 to reject the pension changes.