The HSE has now confirmed that the three hospitals, which reported infections earlier this morning, were NOT from the WannaCry ransomware virus.
The executive says the 20 machines were quickly isolated from networks - before it spread - with the machines replaced and the systems put back online.
The HSE network will remain isolated for a further 48 hours to maintain protection from the attack.
The ransomware attack has been detected in around 200,000 computers in at least 150 counties since it began on Friday
The HSE says their systems cannot recieve emails from external sources but the impact on patients is minimal.
Susan Keogh has been speaking to the Technology Editor with the Irish Independent Adrian Weckler:
