The HSE says the cyber-attack will continue to affect the health service for 'many more weeks' - despite some computer systems being restored.
It's warning people to expect thousands of appointments to be cancelled again next week.
Outpatient and radiology consultations will continue to be called off - and emergency departments will still experience long delays.
The HSE's chief operations officer, Anne O'Connor, says the problem will take a long time to solve.
"There's a lot of work still to be done, and we know it's going to extend for many more weeks.
"There will be an incremental improvement, however the restoration of services and systems will be patchy, a nd we know that services will gradually return on a piecemeal basis around the country.
"We expect to have challenges for a number of weeks - we're going to have a lot of catch up to do, we're already ten days into this, and we're going to have to restore patient records once the systems return."
