More than 100,00 people will be notified from today their data was compromised in the HSE ransomware attack in May last year.
Those affected will receive a letter between now and April 2023 informing them.
The HSE's Chief Information Officer Fran Thompson, explained that Gardaí managed to secure the data targeted by the hackers and return it to the HSE.
They then worked to verify the information and identify those impacted.
113,000 people will receive a letter from the HSE between now and April of next year.
84% of the data was that of patients, while 16% of it related to staff. It is a mix of personal, medical, employee and limited financial information.