The General Manager of Letterkenny University Hospital says work is ongoing to diagnose the extent of the HSE's cyber attack.
Dialysis services and vaccination clinics are operating as normal at the hospital.
As is hematology and oncology clinics, unless contacted by the hospital to advise otherwise.
All other services at Letterkenny University Hospital have been suspended including diagnostic services.
Patients are advised not to attend their scheduled appointment unless contacted by the hospital.
Sean Murphy says the full impact of the cyber attack has resulted in a further restriction of services: