ACC has admitted the personal information of 35 of its clients was stolen from a case manager's house in Christchurch.
ACC's General Manager Claims Management, Sid Miller, says a handwritten notebook with case details and a range of personal information about clients was taken during a burglary on the 3rd of August.
He says ACC yesterday started contacting clients that may have been affected by the theft to apologise.
"We are committed to keeping affected clients fully informed, and to resolve any issues that might arise for them from this situation.
"At this point we believe that the details of 35 clients are likely to be in the notebook. We are also contacting a further 89 clients as a precaution. We believe it is unlikely that their details are in the notebook, but they were clients of the case manager this year. So far we have contacted 83 people.
Mr Miller said the affected clients were all shorter-term, rehabilitation clients who had contacted ACC in the last 12 months.
"At this point we do not know if anyone has looked at the notebook. It is possible that the burglar discarded it because it has no value to them."