Patients could face more "significant disruption" as industrial action at some Northern Ireland hospitals is expected to continue next week.
The Belfast Health Trust has cancelled 900 routine outpatient appointments on Monday.
All hospital surgical procedures, inpatient and day cases will proceed as normal in its hospitals.
Outpatient appointments are cancelled in the Royal Victoria Hospital, Belfast City Hospital and School of Dentistry.
All other outpatient appointments in Musgrave Park, the Mater, the Royal Belfast Hospital for Sick Children, Royal Jubilee Maternity and the Northern Ireland Cancer Centre are due to go ahead as normal on Monday.
The Belfast Trust anticipates there will be significant disruption to services on Tuesday and Wednesday "with a number of outpatient appointments and a number of inpatient and day case treatments cancelled".
The latest information on disruptions and cancellations is available on the Health and Social Care website.
'Unsafe' staffing levels
Industrial action continued on Friday after health workers rejected a new pay offer.
Richard Pengelly, from the Department of Health, said he was desperately disappointed the offer, which involved an extra £28m, was turned down.
Health workers are unhappy at pay and staffing levels, which they claim are "unsafe".
The Health and Social Care Board said further action was planned by Unison, with the Royal College of Nursing also planning industrial action short of a strike from 10-11 December.
It added all health organisations would "continue to work closely together to mitigate the effects of any disruption from industrial action with a strong focus on public safety".
'Going to get worse'
Speaking at Antrim Area Hospital on Friday, Unison's Stephanie Greenwood said members had been "insulted" by the new offer.
Ms Greenwood said she hoped a statement from the department that no further pay offers would be made this year had been made "in the heat of the moment".
"I left a hospital ward this morning with 27 patients being nursed by three nurses and two nursing auxiliaries," she said.
"That is not safe staffing and it is going to get worse as the industrial action progresses."
Speaking to Good Morning Ulster, Pat Cullen, director of the Royal College of Nursing in Northern Ireland, said the talks had been a "step in the right direction" but the pay offer "doesn't reach parity with England".
She said talks could resume "when more money is on the table" and there was a concern from members of her union that they were being used as "political footballs in a bigger system".
All of Northern Ireland's health trusts have said the action was likely to result in a "significant risk to patient safety".