In each of the 10 cases, other specimens subject to coronial review had previously been returned to the families.
The Chief Coroner was advised late last week of the accidental retention of samples and his office contacted families today.
"There are a small number of cases where accidental retention of tissue has occurred after the coroner has completed investigations and we acknowledge the distress this will cause,'' Dr Wilsher said.
"It is clear that we must improve our systems to ensure no other families find themselves in this position in future.''
Dr Wilsher said the DHB had already begun implementing systemic changes to improve the detailed recording of tissue samples.
The retention of some post-mortem tissue samples was discovered in a forensic pathology department audit.
The findings were then cross-referenced to confirm accuracy.
The audit identified that tissue including small samples of organ tissue, blood and gastric contents had been stored after they were cleared to be returned to families.
The DHB said factors contributing to the tissues being retained include storage in multiple locations and records held on multiple databases, manual recording of specimens and staff resourcing issues.
Dr Wilsher said affected families would be contacted, with offers to meet those wishing to have further discussions.
The Department of Forensic Pathology within Auckland DHB's LabPLUS is New Zealand's largest mortuary service, handling an average of 865 post-mortem cases each year.
After the Coroner's Act 2006 came into effect in July 2007, tissue was required to be returned to family members of the deceased if requested by them and if directed by the coroner following the finalisation of investigations.
