Patients needing urgent brain surgery are being turned away from Beaumont Hospital in Dublin.
The national neurosurgical centre had no beds for nine patients with malignant brain tumours last Friday.
Head of the unit Doctor Mohsen Javadpour told the Irish Times patients were deteriorating at home while waiting for treatment.
The latest figures show more than 6,000 patients were waiting on trolleys in hospitals around the country last month.
General Secretary of the Irish Nurses and Midwives Organisation Liam Doran said: "It's appalling and an indictment on Irish society…We do not have a public health service that's fit for purpose."