Nearly 200 gravestones in two Flintshire cemeteries will be laid flat or temporarily secured after they were found to be a "high risk" to the public.
Checks by the council revealed 198 were in danger of falling over and injuring people at Bagillt and Holywell.
Families will be contacted if possible and notices placed on memorials.
The council said it would be securing lawn-type memorials until grave owners could arrange for them to be repaired.
The local authority said it checked memorials every three years to see if any pose a potential danger.
A statement said: "The owners of these memorials will be contacted where possible and notices placed on the memorial.
"Older headstones over 1.5 metres high including kerbed memorials which were identified as dangerous will be laid flat and a notice placed on the grave to notify the family why this action is required in the interests of health and safety.
"The Local Authorities' Cemeteries Order 1977 empowers a burial authority to take any action that is necessary to remove a danger that arises by means of the condition of a memorial."
Work will begin on 30 August.
Anybody with questions can call the Bereavement Services Office on 01352 703360 or 703361 or 703362.