Mullingar Regional Hospital has apologised to the family of a patient, who were given the wrong remains.
The hospital has confirmed the incident in the mortuary of the hospital last Friday.
It said this saw the release of "incorrect remains" to an undertaker.
It said the mistake has since been rectified.
The Ireland East Hospital Group and Regional Hospital Mullingar are conducting a full internal review.
They have also convened their Serious Incident Management Team.
In a statement, Ireland East Hospital Group said: "We would like to offer our condolences to the families and sincerely apologise for the distress this has caused during this difficult time."
"Processes and protocols have been reviewed within the hospital and its mortuary in order to mitigate this extremely rare event from happening again."