Personal information belonging to dozens of vulnerable people receiving government-funded home care on the Isle of Man has been lost.
Paper records of phone numbers, names and addresses of 33 adults had been "mislaid", the Department of Health and Social Care admitted.
Codes to access the keys to seven people's homes were also lost.
The department said it had reported the "breach" to the Information Commissioner.
It also said the missing key codes had been changed.
Phone numbers for 43 people listed as next of kin and 11 carers have also disappeared.
The data loss is the first of its kind within the government's home care service.
A spokesman for the department said those affected were "predominately older people" from the Douglas area and they were being contacted individually.
However, former health minister Kate Beecroft MHK said the breach was a "very serious matter" and "should not have happened".
The Information Commissioner's office said it was "satisfied with the steps taken so far" by the department "to mitigate the risk" to those affected.
There are 159 people receiving services across the island.
Head of operations for adult social care Jonathan Carey said they were "some of the most vulnerable people in our society" and a "thorough investigation" had been launched.
All other paper records have now been "secured safely", he added.
It is not known how long the information was missing before the key codes were changed.
A police spokesman said the matter had not been reported to the force as it was not considered a criminal act.