A 12-hour strike that has already led to cancelled surgeries in NSW hospitals cannot go ahead, the state's industrial relations commission has ruled.
But nurses and midwives still plan to walk off the job in their thousands for 12 hours on Tuesday after demands for a 15-per-cent pay rise this year were rebuffed.
Life-preserving staffing was to be maintained but longer waits in emergency departments and planned surgery cancellations were expected.
NSW Health, which had begun contacting patients about postponing surgeries, challenged the strike in the state's industrial relations commission on Monday, emerging victorious late in the afternoon.
The commission had ordered the NSW Nurses and Midwives' Association to cease the strike action immediately, Health Minister Ryan Park said.
"Unions fought for this independent industrial court and commission, and we continue to urge the association to comply with the orders," he said.
"There is no doubt such action will impact our public health system, from longer waits in emergency rooms to cancelled non-emergency surgeries."
But the union said the orders would not stop Tuesday's action.
"Nurses and midwives do not take industrial action lightly," general secretary Shaye Candish said.
"They strive to provide compassionate, high-quality care to our patients every day, but the NSW government's refusal to value us and put a decent offer on the table has left us with no choice."
It said the government had not negotiated on a pay rise above their three-per-cent offer.
That was despite the union identifying $3 billion in lost federal funding that it says could cover its demand for a 15-per-cent jump for its members.
"We will continue to fight for fair pay until a meaningful offer is delivered," Ms Candish said.
Opposition leader Mark Speakman said it was shocking a government "claiming to care about essential workers" could let it get to this point.
The strikes come as Labor juggles multiple battles with industrial unions over pay, having convinced most in 2023 into a snap, one-year deal for a four-per-cent wage rise.
Rail workers are also threatening to derail plans to bring driverless trains to Sydney's south.
The rail union on Monday formally applied to begin work bans on September 18 unless rail fares were reduced to 50 cents per trip.
