There were 363 data-protection breaches recorded by the HSE in the first ten months of this year.
Patients' records were found in recycling bins, public streets and car parks.
The details have been released under the Freedom of Information Act.
There were several instances of patients' information sent to the wrong people.
A patient's record relating to Mallow General Hospital was found in a public car park and a patient list was found on a street in Cork.
A patient's records from Cork University Maternity Hospital were found in a recycling bin.
Two children's health records were lost in Kerry.
A patient's medical file from Letterkenny University Hospital was found by a person in a public park.
A HSE interview board member accidentally left a package, with 18 candidate application forms, at a train station.
Documents relating to St Luke's in Kilkenny were found in a bag given to a HSE-funded charity shop.
Two insurance claims connected to Wexford Hospital were sent to the wrong insurance company.
A form from an addiction service was lost in transit to a lab.
A patient list from Our Lady of Lourdes Hospital in Drogheda was found by a member of the public at the gate of a hospital.
"Clearly there is a very large number of data breaches here and it is a major cause for concern," said Stephen McMahon is from the Irish Patients Association.
"Any breach of personal private information can be absolutely shattering for the individual patient and their family."
The HSE says it takes all breaches of data protection seriously and all cases are fully investigated.