The government says it has hundreds of experts working to rebuild HSE systems and find those responsible for the cyber attack on its network.
The Taoiseach last night told his parliamentary party it's crucial that access to radiology, diagnostics and therapeutics is restored.
Hospitals are prioritising emergency cases, and patients in need of non-urgent care are being told to expect long delays.
Meanwhile it's reported hackers have already begun sharing people's private and sensitive information online.
