Hundreds of appointments and services have been hit as nurses take to the picket lines across Northern Ireland for the second time in a week.
Health trusts across the North cancelled or postponed appointments and services on Tuesday due to the second planned 12-hour strike by the Royal College of Nursing (RCN).
It comes after a 12-hour strike last Thursday across Northern Ireland, England and Wales.
Nurses are taking the action over pay and safe staffing levels.
The RCN has been calling for a pay rise of 5 per cent above inflation, though it has indicated it would accept a lower offer.
"It's for the sake & the future of the NHS. If we don't do something about it now it will fall apart."
Today nursing staff are back on picket lines. Their fight is all our fight.
Are you still with them?
Share this video to say yes.#RCNStrike #FairPayForNursing #NursesStrike pic.twitter.com/K0xcXvjHF3— The RCN (@theRCN) December 20, 2022
The UK government has implemented the recommendations of the independent pay review body, which gave nurses an increase of about 4.75 per cent, with a guaranteed minimum of £1,400 (€1,600).
UK health secretary Steve Barclay has declined to discuss pay when meeting union officials but said his door is open to discuss other areas of nursing.
Emergency departments are among the areas exempt from the industrial action.
However, the walkouts have affected hundreds of patients across Northern Ireland.
In the Belfast Health Trust, some 175 new outpatient appointments, 289 outpatient reviews and 26 inpatient day cases were cancelled.
The South Eastern Trust said 17 endoscopy investigations were postponed, 15 surgical procedures cancelled, 229 outpatient appointments cancelled and the minor injuries unit at Ards Hospital will be closed on Tuesday.
The Southern Trust said 204 outpatients appoints were cancelled, 28 day cases and nine inpatient appointments were cancelled, while 448 appointments would not go ahead within the older people and primary care division, and the minor injuries service at South Tyrone Hospital is closed on Tuesday.
It said emergency departments at Craigavon Hospital and Daisy Hill in Newry will remain open, but are likely to be busy.
In the Western Trust some 515 outpatient appointments were postponed, and 37 planned inpatient and day case procedures were cancelled, and in the Northern Trust 154 outpatient appointments were affected.