More than 300 nurses and midwives across NSW have walked off the job to protest unsafe work conditions and what they say is a paltry pay rise offer.
In Sydney, more than 100 nurses and midwives have left Liverpool Hospital after voting to stop work for four hours on Thursday afternoon.
Workers are also striking at nearby Campbelltown Hospital, with around 60 staff members walking off the job for two hours.
Around 150 nurses and midwives in Lismore have taken strike action, and won't return to work until 7am on Friday.
The action comes after NSW paramedics on Thursday also went on strike, attending life-threatening jobs but eschewing less serious incidents like a broken arm.
The NSW Nurses and Midwives Association and the Health Services Union both face fines over the strikes, after the NSW Industrial Relations Commission last week ruled they could not undertake lawful industrial action until at least June 30.
NSW Nurses and Midwives Association general secretary Brett Holmes says the industrial action wasn't a decision taken lightly.
He says some staff at Liverpool Hospital have even received verbal threats to their employment over their involvement in the strike.
"But whenever our members are outside a hospital there is something wrong inside," he told AAP.
"Government and management seem to have their heads in the sand, thinking everything is OK in the hospital system ... but our members know that patients are at risk and their efforts are not enough to keep them safe."
In all three hospitals "life preserving" numbers have remained at work.
The absence of staff-to-patient ratios, excessive workloads and an inordinate amounts of overtime have pushed many nurses and midwives to the brink of walking away from the profession, Mr Holmes said.
Adding to the frustration is the feeling their concerns are falling on deaf ears and the "insulting" 1.04 per cent annual pay rise offer made by the government.
The protest follows several other strikes over the past fortnight, and Mr Holmes says other branches will meet across the state in the coming days to consider their action.
But a spokesperson for NSW Health said the ratios union members are requesting do not reflect modern rostering practices, and more nurses and midwives are employed in the state's public hospitals than ever before.
"The complexity of a hospital and its patients, as well as the professional judgement of nurses and managers is what decides staffing levels," the spokesperson said in a statement.
"The current ... staffing system is a flexible ratio which enables nursing staff to be redeployed where patient need is greatest."
The union's demands also include a 4.7 per cent pay increase and free parking for nurses and midwives across the state health network, the spokesperson said.
"NSW Health has not accepted this claim and has instead offered a wage increase consistent with the government's state-wide public sector wages policy and which reflects the prevailing economic conditions more broadly."
Health Minister Brad Hazzard have been contacted for comment.
Australian Associated Press