The Health Service Executive (HSE) recorded over 2,000 data breaches last year.
They include patients' files getting lost and hospital charts going missing.
According to Freedom of Information files released to Newstalk, 2,035 data breaches were recorded by the health service in 2021.
Many were because patients' files went missing, were sent to the wrong service-users, incorrect GPs or pharmacies.
In one case, a list of patients was found on the grounds of Galway University Hospital.
And a similar document, from Letterkenny University Hospital, was located outside a public premises.
In a data breach in Sligo, personal data was wrongly shared with a client's ex-partner.
A folded letter from BreastCheck was franked and posted without an envelope.
Solicitor Jason O'Sullivan says many data-breaches are down to human error.
"Although the level of breaches, they appear quite minor - such as post going to the wrong address - they can still have a negative impact on patients causing them to miss important appointments, for instance.
"The quite large number of breaches across the country does denote the sheer scale of sensitive data the HSE deal with daily".
There were over 1,000 data breaches relating to the Digital COVID Certificate - with people getting them by mistake as a result of errors with processing.